DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 

PROFESSIONAL PAPER 119 

REPTILIAN FAUNAS OF THE TORREJON, PUERCO, AND 


UNDERLYING UPPER CRETACEOUS FORMATIONS 


OF SAN JUAN COUNTY, NEW MEXICO 


BY 

CHARLES W. GILMORE 

WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1919 

t 

41: 

. • 

(el -1,4, 

••-.• ,11 

1,11(`;•-•'• 

cr, 

17" 

„.• 

• 

, 

,e• 5.4 

•-•••'•., 

'4" 

`1. 
DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 

Professional Paper 119 

REPTILIAN FAUNAS OF THE TORREJON, PUERCO, AND 


UNDERLYING UPPER CRETACEOUS FORMATIONS 


OF SAN JUAN COUNTY, NEW MEXICO 


BY 

CHARLES W. GILMORE 

WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1919 
ADDITIONAL COPIES 

OF THIS PUBLICATION MAY BE PROCURED FROM 

THE SUPERINTENDENT OF DOCUMENTS 

GOVERNMENT PRINTING OFFICE 

WASHINGTON, D. C. 


AT 


40 CENTS PER COPY 


V 
CONTENTS. 

Introduction 

The reptilian faunas of the Upper Cretaceous and basal Eocene formations of the San Juan Basin 

Fruitland fauna 

Kirtland fauna 

Ojo Alamo fauna 

Basal Eocene fauna 

Turtles 

The faunas 

Order Chelonia 

Family Pleurosternidae 

Genus Neurankylus Lambe 

Neurankylus baueri Gilmore 

Genus Compsemys Leidy 

Compsemys parva Hay. 

Compsemys vafer Hay 

Compsemys puercensis Gilmore, n. sp 

Compsemys torrejonensis Gilmore, n. sp 

Family Baenidae 

Genus Baena Leidy 

Baena nodosa Gilmore 

Baena sp. undet 

Family Dermatemydidae 

Genus Adocus Cope 

Adocus kirtlandius Gilmore, n. sp 

Adocus bossi Gilmore, n. sp 

Adocus hesperius Gilmore, n. sp 

Adocus onerosus Gilmore, n. sp 

Adocus annexes (Hay) Gilmore 

Genus Hoplochelys Hay 

Hoplochelys crassa (Cope) Hay 

Hoplochelys bicarinata Hay 

Hoplochelys laqueata Gilmore, n. sp 

Hoplochelys saliens Hay 

Hoplochelys elongata Gilmore, n. sp 

Superfamily Trionychoidea 

Family Plastomenidae 

Genus Plastomenus Cope 

Plastomenus robustus Gilmore, n. sp 

Plastomenus torrejonensis Gilmore, n. sp 

Family Trionychidae 

Genus Aspideretes Hay 

Aspideretes reesidei Gilmore, n. sp 

Aspideretes vegetus Gilmore, n. sp 

Aspideretes quadratus Gilmore, n. sp 

Aspideretes perplexes Gilmore, D. sp 

Aspideretes sagatus Hay 

Genus Amyda Oken 

Amyda eloisae Gilmore, n. sp. 

Page. 

7 

7 

8 

8 

8 

9 

10 

11 

11 

11 

11 

11 

12 

13 

16 

19 

21 

24 

24 

24 

24 

25 

25 

26 

29 

33 

35 

37 

40 

41 

43 

47 

49 

50 

52 

52 

52 

53 

55 

56 

56 

56 

57 

59 

60 

61 

62 

63 

3 
4 CONTENTS. 

The faunas—Continued. 

Order Dinosauria 

Suborder Predentata 

Family Hadrosauridae 

Subfamily Hadrosaurinae 

Subfamily Saurlophinae 

Family Ceratopsidae 

Genus Ceratops 

Ceratops sp 

Ceratopsian, genus and species undetermined 

Family Scelidosauridae 

Genus and species undetermined -

Suborder Theropoda 

Family Megalosauridae 

Genus and species undetermined 

Order Crocodilia 

Class Pisces 

Genus Lepisosteus Lacepede 

Lepisosteus sp 

Index 

Page. 

64 

64 

64 

64 

64 

64 

64 

64 

65 

65 

65 

67 

67 

67 

67 

68 

68 

68 

71 
ILLUSTRATIONS. 

Page. 

PLATES I-XXVI. Fossil reptiles from San Juan County, N. Mex 70 

FIGURE 1. Carapace and plastron of Compsemys parva Hay 13 

2. Carapace and plastron of Compsemys vafer Hay 17 

3. Carapace and plastron of Compsemys puercensis Gilmore, n. sp 19 

4. Comparative view of plastra: A, Compsemys torrejonensis; B, Compsemys puercensis; C, Compsemys 

parva; D, Compsemys vafer 20 

5. Carapace and plastron of Compsemys torrejonensis Gilmore, n. sp 21 

6. Shell of Compsemys torrejonensis 22 

7. Carapace of Adocus kirtlandius Gilmore, n. sp. 27 

8. Plastron of Adocus kirtlandius Gilmore, n. sp 28 

9. Carapace of Adocus bossi Gilmore, n. sp. 30 

10. Plastron of Adocus bossi Gilmore, n. sp 31 

11. Carapace of Adocus hesperius Gilmore, n. sp 34 

12. Carapace of Adocus onerosus Gilmore, n. sp 35 

13. Plastron of Adocus onerosus Gilmore, n. sp 36 

14. Plastron of Adocus annexus (Hay) 38 

15. Plastron of Adocus annexus (Hay) 38 

16. Carapace of Hoplochelys crassa (Cope) 42 

17. Carapace and plastron of Hoplochelys bicarinata Hay 43 

18. Carapace of Hoplochelys bicarinata Hay 44 

19. Carapace and plastron of Hoplochelys laqueata Gilmore, n. sp 48 

20. Carapace of Hoplochelys laqueata Gilmore, n. sp 49 

21. Carapace and plastron of Hoplochelys elongata Gilmore, n. sp. 51 

22. Carapace of Hoplochelys elongata Gilmore, n. sp 52 

23. Carapace of Plastomenus robustus Gilmore, n. sp 53 

24. Plastral bones of Plastomeny robustus Gilmore, n. sp 54 

25. Carapace of Plastomenus torrejonensis Gilmore, n. sp 55 

26. Carapace of Aspideretes reesidei Gilmore, n. sp 56 

27. Carapace of Aspideretes vegetus Gilmore, n. sp 58 

28. Plastron of Aspideretes vegetus Gilmore, n. sp ' 59 

29. Carapace of Aspideretes quadrates Gilmore, n. sp 60 

30. Carapace of Aspideretes perplexus Gilmore, n. sp 61 

31. Plastral bones Aspideretes sagatus Hay 62 

32. Carapace of Amyda eloisae Gilmore, n. sp. 63 

33. Skin plates of an armored dinosaur 66 

REPTILIAN FAUNAS OF THE TORREJON, PTJERCO, AND UNDERLYING TIPPER 


CRETACEOUS FORMATIONS OF SAN JUAN COUNTY, NEW MEXICO. 


By CHARLES W. GILMORE.1 

INTRODUCTION. 

The present paper, which in some respects is 

supplementary to another recent one on the 

same region,2 is based on a series of vertebrate 

remains collected during the field season of 

1916 for the United States Geological Survey 

by J. B. Reeside, jr., and F. R. Clark. Specimens were collected at several horizons in the 

Puerco, Torrejon, Ojo Alamo, Kirtland, and 

Fruitland formations at many localities in San 

Juan County, N. Mex. This collection is especially rich in turtle remains. In the number 

of specimens and the excellent state of their 

preservation it forms the best single collection 

of fossil turtles that has ever been made in the 

southwestern United States, and Mr. Reeside 

and Mr. Clark are to be highly commended for 

the industry and skill they displayed in bringing it together. 

The recovery of nearly perfect individuals 

pertaining to Compsemys, Hoplochelys, and 

Adocus—genera which, prior to this time, were 

known only from very fragmentary materials— 

forms a distinct contribution to our knowledge 

of the skeletal anatomy of these extinct turtles. 

Furthermore, the presence in the collection of 

good specimens representing species of the 

same genera from successive geologic formations is of the greatest interest for study of the 

structural changes that may have taken place 

in a genus over considerable periods of time. 

Sixteen new species of extinct turtles are 

described in the present paper, the greater 

number of which pertain to the Puerco and 

Torrejon formations. The faunas of the San 

Juan area are yet but imperfectly known, and 

1 Associate curator of the division of paleontology, U. S. National 

Museum. 

2 Gilmore, C. W., Vertebrate faunas of the Ojo Alamo, Kirtland, and 

Fruitland formations: U. S. Geol. Survey Prof. Paper 98, pp. 279-308 

1916. 

the region is by no means exhausted. Careful 

collecting is certain to yield many new forms 

and more perfect specimens of others now imperfectly known. 

The recovery of additional though incomplete dinosaur specimens from the Upper Cretaceous formations is of interest as showing the 

presence of forms other than those reported in 

my paper of 1916.3 Some of these specimens 

give corroborative evidence bearing on the 

earlier conclusion that the formations from 

which they came is of Montana age. 

I take this opportunity to acknowledge my 

indebtedness to Dr. W. D. Matthew, of the 

American Museum of Natural History, New 

York, for the loan of type specimens. I am 

especially under obligations to Dr. 0. P. Hay 

for invaluable advice and assistance on numerous occasions, and to Messrs. N. H. Boss and 

Louis Goldberg, preparator and assistant preparator in the section of vertebrate paleontology, United States National Museum, for their 

efficient work in preparing for study the specimens forming this collection. 

THE REPTILIAN FAUNAS OF THE UPPER CRETACEOUS AND BASAL EOCENE FORMATIONS 

OF THE SAN JUAN BASIN. 

The vertebrate faunas of the Ojo Alamo, 

Kirtland, and Fruitland formations were so 

fully reviewed in the paper already cited that 

at present it seems necessary only to record 

the additional information obtained from a 

study of the specimens procured by the Reeside expedition during the summer of 1916. 

The reptilian faunas of the Puerco and Torrejon formations, however, are reviewed at 

somewhat greater length, not only on account 

of their apparent neglect for many years, but 

3 Gilmore, C. W., op. cit., p. 280. 

7 
8 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

also because of the notable contribution to our 

knowledge of those faunas furnished by specimens in this collection. 

Beginning with the Fruitland, the oldest f ormation from which vertebrate fossils were obtained in this area, these faunas are discussed 

successively below in the order in which they 

occur in the geologic section. 

FRUITLAND FAUNA. 

The list of extinct turtles in the Fruitland 

formation is increased by the discovery of a 

member of the family Baenidae, provisionally 

identified as Baena nodosa? Gilmore, a species 

founded on a specimen from the Kirtland formation. In the published 1 faunal list of the 

Fruitland formation,' Adocus? lineolatus Cope 

was included. The identification of this species 

rested on a peripheral bone having a sculpture 

indistinguishable from the type of the species. 

Materials in the present collection show that 

the character of the sculpture can not be depended on for specific determinations in the 

genus Adocus, and in the revised list below the 

species name is dropped. Likewise the interrogation mark following the generic name is no 

longer used, for the discovery of well-preserved 

specimens shows that the genus is present in 

this formation. 

Fruitland formation: 

Dinosauria: 

Monocloniu,sf 

Carnivorous dinosaur. 

Chelonia: 

Adocus sp. 

Aspideretes sp. 

Baena nodose Gilmore. 

Pisces: 

Lepisosteus sp. 

KIRTLAND FAUNA. 

Vertebrate fossils appear to occur most 

abundantly in the upper part of the Kirtland 

formation and sparsely in and below the 

Farmington sandstone member. 

In the present collection there are three new 

species of turtles from this formation, though 

the genera to which they pertain have all been 

previously recognized. Fragmentary specimens show the presence of other unrecognized 

and probably undescribed species. 

The dinosaurian remains, though incomplete 

specimens, are of importance because they 

Gilmore, C. W., op. eit., p. 280. 

furnish corroborative evidence in support of 

the former contention that the Kirtland formation is of Montana age. This evidence consists in the presence of individuals of the 

horned Dinosauria or Ceratopsia provisionally 

identified as belonging to the genus Ceratops, 

for, regardless of the uncertainty of the generic 

identification, these specimens show a stage of 

development reached only in the Judith River 

and Belly River ceratopsians. 

Additional evidence along the same line is 

afforded by the duck-billed or trachodont 

specimens in the collection—for example, the 

trachodont ischia of the footed and nonfooted 

kinds, which indicate the crested and noncrested types of skulls. The crested trachodonts, a type of development not known to 

occur in beds later than the Edmonton, are 

now first recognized in this formation. Trachodont dentaries in the collection showing a 

reduced number of rows of teeth as compared 

with those from the Lance formation also 

indicate a greater antiquity for these forms. 

The revised faunal list as known at this time 

is given below. 

Kirtland formation: 

Dinosauria: 

Kritosaurus navajovius Brown. 

Crested trachodonts. 

Carnivorous dinosaurs. 

Ceratops? sp. 

Armored dinosaur (Scelidosauridae). 

Chelonia: 

Baena nodosa Gilmore. 

Baena sp. 

Neurankylus baueri Gilmore. 

Adocus bossi Gilmore, n. sp. 

Adocus kirtlandius Gilmore, n. sp. 

Plastomenus robustus Gilmore, n. sp. 

Plastomenus sp. 

Aspideretes sp. 

Crocodilia: 

Crocodylus sp. 

Brachychampsa sp. 

Pisces: 

Lepisosteus sp. 

Myledaphus sp. 

OJO ALAMO FAUNA. 

The faunal list of the Ojo Alamo formation 

is increased by the discovery of a few bones of 

an armored dinosaur, the first to be recorded 

from this formation. Although the remains 

are too scanty for close identification, their 

nearest affinities are unquestionably with 

those members of this group found. in the 
THE FAUNAS. 9 

more ancient formations rather than with 

Ankylosaurus of the Lance formation. 

ojo Alamo formation: 

Dinosauria: 


Kritosaurus navajovius Brown. 


Monoclonius sp. 


Armored dinosaur. 


Deinodon? 


Chelonia: 


Basilemys nobilis Hay. 


Adocus vigoratus Hay. 


Aspideretes vorax Hay. 


Aspideretes fontanus Hay. 


Aspideretes austerus Hay. 


Thescelus rapiers Hay. 


Compsemys sp. 


Crocodilia: 


Crocodylus sp. 


Pisces: 


Lepisosteus sp. 


BASAL EOCENE FAUNA. 

All the described reptiles of the Puerco and 

Torrejon formations have been made known 

by the work of two paleontologists. Prof. E. 

D. Cope described the first materials, foundsnake, and a crocodile. Unfortunately all the 

species were founded on scanty and in part ining several species of the aquatic lizard 

sosaurus 

adequate materials. In recent years Dr. 0. P. 

and one species each of a turtle, a 

ChampHay has added a considerable number to the 

known species of turtles. 

The present collection of reptile remains furnishes the most important single contribution 

ever made to our knowledge of these reptilian 

faunas. No less than 11 new species of turtles 

are recognized, in addition to the several described forms represented by specimens so well 

preserved that now all the important features 

of the shells can be fully determined. Representatives of two families, the Pleurosternidae 

and Plastomenidae, each represented by two or 

more species, are recognized for the first time 

in these faunas. 

W. D. Matthew,' who has published the only 

complete faunal list of recent years, sums up 

the reptilian part of the basal Eocene fauna 

as follows: 

The reptiles are chiefly Chelonia, Crocodilia, and Choristodera. One snake has been recorded; lizards were 

1 Matthew, W. D., Evidence of the Paleocene vertebrate fauna on the 

Cretaceous-Tertiary problem: Geol. Soc. America Bull., vol. 25, p. 383, 

1914. 

present. * * * The reptiles all belong to families 

that originated in the Cretaceous (Belly River) or earlier. 

Three of the families still survive; one disappeared with 

the Eocene, another with the Paleocene. 

The mammalian faunas of the Puerco and 

Torrejon have been studied from large collections, and the distinctness of the two faunas 

has been clearly demonstrated through the excellent work of Dr. Matthew and his associates 

in the American Museum of Natural History, 

New York. 

In recent years the reptilian part of these 

faunas has been almost entirely neglected by 

paleontologists, so that the excellent materials 

in the present collection, which add greatly to 

the knowledge of described forms based on 

fragmentary specimens and furnish a considerable number of new species, lay the foundation of faunal lists that will eventually be valuable adjuncts to the mammalian evidence as 

horizon indicators. 

So far as known at present, while all the 

reptilian families and most of the genera passed 

through from the Puerco to the Torrej on, very 

few species survived from one to the other, 

and the few occurrences recorded may be due 

to incorrect identification. 

The large aquatic lizard Champsosaurus, the 

many turtles, all of which are marsh and river 

varieties, and the single snake, which Osborn 2 

says "is unspecialized in character and of about 

the size of the common black snake," all 

indicate the lowland nature of their habitat. 

The complete faunal list of the known 

reptiles of the Puerco and Torrej on formations 

is given below: 

Puerco formation: 

Chelonia: 

Family Pleurosternidae: 

Compsemys parva Hay. 

Compsemys vafer Hay. 

Compsemys puercensis Gilmore, n. sp. 

Family Baenidae: 

Baena sp. 

Family Dermatemydidae: 

Adocus hesperius Gilmore, n. sp. 

Hoplochelys crassa (Cope). 

Hoplochelys bicarinata Hay. 

Hoplochelys laqueata Gilmore, n. sp. 

Family Plastomenidae: 

Plastomenus sp. 

2 Osborn, EL F., The age of mammals, p. 106, 1910. 
��

��

��

��

��

��

��

��

��

��

��

��

10 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

Puerco formation—Continued. 

Chelonia—Continued. 

Family Trionychidae: 

Aspideretes sagatus Hay. 

Aspideretes puercensis Hay. 

Aspideretes reesidei Gilmore, n. sp. 

Aspideretes vegetus Gilmore, n. sp. 

Aspideretes quadratus Gilmore, n. sp. 

Aspideretes perplexus Gilmore, n. sp. 

Conchochelys admirabilis Hay. 

Rhynchocephalia: 

Family Champsosauridae: 

Champsosaurus australis Cope. 

Champsosaurus saponensis Cope. 

Loricata: 

Family Crocodylidae: 

Crocodylus stavelianus Cope. 

Pisces: 

Family Lepisosteidae: 

Lepisosteus sp. 

Torrejon formation: 

Chelonia: 

Family Pleurosternidae: 

Compsemys torrejonensis Gilmore, n. sp. 

Compsemys parva? Hay. 

Family Baenidae: 


Baena escavada Hay. 


Baena sp. 


Family Dermatemydidae: 

Adocus substrictus (Hay) 

Adocus onerosus Gilmore, n. sp. 

Adocus annexus (Hay). 

Hoplochelys saliens Hay. 

Hoplocheleys paludosa Hay. 

Hoplochelys elongata Gilmore, n. sp. 

Family Plastomenidae: 

Plastomenus acupictus Hay. 

Plastomenus n. sp.? 

Plastomenus sp. undet. 

Family Trionychidae: 

Aspideretes singularis Hay. 

Aspideretes sp. 

Platypeltis antiqua Hay. 

Amyda eloisae Gilmore, n. sp. 

Serpentes: 


Helagras prisciformis Cope. 


Rhynchocephalia: 


Family Champsosauridae: 

Champsosaurus puercensis Cope. 

Champsosaurus saponensis Cope. 

Loricata: 


Family Crocodylidae: 


Crocodylus sp. 


Pisces: 


Family Lepisosteidae: 


Lepisosteus sp. 


TURTLES. 

Identified turtle .specimens collected by J. B. Reeside in San 

Juan County, N. Mex., 1916. 

Name. 

Neurankylus baueri Gilmore 

do 

Compsemys parva Hay 

Compsemys parva? Hay 

Compsemys vafer Hay 

do 

do 

Compsemys puercensis Gilmore, n. 

sp. 

Compsemys torrejonensis Gilmore, 

n. sp. 


do 


do 


Baena nodosa Gilmore. - do 

do 

Baena escavada? Hay 

Baena sp 

do 

Adocus bossi Gilmore, n. sp 

do 

Adocus kirtlandius Gilmore, n. sp. 

Adocus hesperius Gilmore, n. sp 

Adocus onerosus Gilmore, n. sp 

do 

do 

Adocus annexus (Hay) 

Adocus sp 

do 

Hoplochelys bicarinata Hay 

do 

Hoplochelys crassa (Cope) 

do 

do 

do 

Hoplochelys laqueata Gilmore, n. 

sp.

Hoplechelys elongata Gilmore, n. sp. 

do 

do 

Hoplochelys saliens Hay 

do 

Plastomenus robustus Gilmore, Tl. sp 

Plastomenus torrjeonensis Gilmore, 

n. sp. 

Plastomenus sp 

Aspideretes perplexus Gilmore, n. 

.sp 

Aspideretes reesidei Gilmore, n. sp. 

Aspideretes vegetus Gilmore, n. sp.. 

Aspideretes quadratus Gilmore, n. sp 

Aspideretes sagatus Hay 

Aspideretes sagatus? Hay 

Aspideretes sp 

Amyda eloisea Gilmore, n. sp 

U.S. 

N. M. 

catalogue 

No. 

8621 

8531 

8528 

8598 

8529 

8530 

8600 

8544 

8549 

8597 

8599 

8603 

8622 

8614 

8840 

8623 

8624 

8577 

8613 

8593 

8596 

8594 

8649 

8650 

8606 

8651 

8654 

8524 

8526 

8525 

8641 

8643 

8607 

8527 

8553 

8603 

8609 

8605 

8646 

8538 

8543 

8653 

8532 

8537 

8539 

8545 

8554 

8652 

8555 

8540 

Formation. 

Kirtland. 

Do. 

Puerco. 

Torrejon. 

Puerco. 

Do. 

Do. 

Do. 

Torrejon. 

Do. 

Do. 

Kirtland. 

Do. -

Do. 

Torrejon. 

Kirtland. 

Do. 

Do. 

Do. 

Do. 

Puerco. 

Torrejon. 

Do. 

Do. 

Do. 

Do. 

Kirtland. 

Puerco. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Torrejon. 

Do. 

Do. 

Do. 

Do. 

Kirtland. 

Torrejon. 

Do. 

Puerco. 

Do. 


Do. 


Po. 


Torrejon. 

Do. 

Do. 

Puerco. 
REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 11 

THE FAUNAS. 

Order CHELONIA. 

Turtle remains belonging to five families— 

the Pleurosternidae,. Baenidae, Dermatemydidae, Plastomenidae, and Trionychidae—have 

been recognized in the present collection. 

These specimens pertain to 8 genera and 24 

species. Sixteen of these are described as 

new, 11 of which come from the basal Eocene 

deposits of the San Juan Basin. That there 

are other undescribed forms is indicated by 

fragmentary specimens in. this collection, but 

these are regarded as inadequate type material 

on which to found new species. 

In. studying this collection of extinct turtles, 

much difficulty has been experienced in determining the exact characters which distinguish 

certain described species. For most species 

it has entailed a considerable search through 

the descriptive text and long study and comparison. At the present time more than 300 

species of extinct turtles from North America 

have been described, and rarely has the describer of any particular species given or attempted to give a concise synopsis of the specific 

characters which distinguish that species. In 

order to correct this deficiency I have noted at 

the end of the description of each species in 

the present paper the group of characters which 

in my judgment indicates its specific distinctness. I am satisfied that when more and better 

materials are available, many of the characters 

thus selected will be found to represent individual rather than specific differences. However that may be, this plan has the very great 

advantage of making immediately available 

to later students the characters on which the 

author founded the species, and it establishes 

a definition which may, as our knowledge grows, 

be revised from time to time, so that ultimately 

it will become an accurate specific diagnosis. 

Family PLEUROSTERNIDAE Cope. 

The family Pleurosternidae at the time Hay 

published his " Fossil turtles of North America," 

in 1908, contained the single American genus 

Glyptops. In 1916 the study of excellent mateFruitland formations: U. S. Geol. Survey Prof. Paper 98, p. 290, 1916. 

rankylus 

rial showed the Upper Cretaceous genus 

Gilmore, C. W., Vertebrate faunas of the Ojo Alamo, Kirtland, and 

to be a member of this family.' 

NeuAfter a study of several well-preserved specimens in the present collection pertaining to 

the genus Compsemys I conclude that its 

affinities also,are with the Pleurosternidae rather 

than with the Baenidae as proposed by Hay.2 

The Pleurosternidae therefore now include the 

three genera Glyptops, Neurankylus, and 

Compsemys. 

Genus NEURANKYLUS Lambe, 1902. 

Neurankylus baueri Gilmore. 

Neurankylus baueri Gilmore, Vertebrate faunas of the Ojo 

Alamo, Kirtland, and Fruitland formations: U. S. 

Geol. Survey Prof. Paper 98, pp. 290-293, pls. 74 

and 75, text figs. 32, 33, 1916. 

A very large individual in. the present collection, consisting of the greater part of the 

carapace and plastron (catalogue No. 8531, 

rankylus baueri. 

U.

21 miles south of west of Kimbetoh, in sec. 3, 

T. 

330 feet above the base of the Kirtland 

 S. N. M.), is identified as belonging to 

22 N., R. 10 W., San Juan County, N. Mex., 

The specimen was collected 

Neuformation. 

The chief importance of this specimen lies in 

its being the second individual of the species to 

be found and that it records a new geographic 

occurrence of this species. Its geologic position appears to be about the same as that of the 

type. It is considerably larger than the type 

specimen and has a relatively wider posterior 

lobe at its extremity with a broader truncated 

end and five costal scutes (the fourth divided), 

but it closely resembles the type in most other 

particulars. Some of the principal measurements as compared with those of the type specimen are given below. 

Dimensions of Neurankylus baueri, in millimeters. 

No. No. 8344 8531. (type). 

Greatest length of carapace 635 560 

Greatest width of carapace 530 480 

Greatest length of plastron 449 416 

Length of anterior lobe 119 111 

Width of anterior lobe at base 182 168 

Length of posterior lobe 126 122 

Width of posterior lobe at base 203 185 

Width of posterior lobe at anal-femoral sulcus. 142 113 

Width of bridge. 208 195 

2 Hay, 0. P., Descriptions of eight new species of fossil turtles from 

west of the one hundredth meridian: U. S. Nat. Mus. Proc., vol. 38, p. 308, 

1910. 
12 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

A second specimen (No. 8621, U. S. N. M.), 

consisting of a portion of the posterior end of 

the carapace, is identified as belonging to this 

genus, but I am uncertain as to its specific 

identification. On the median posterior margin 

the edge is rounded and broadly emarginated, 

as contrasted with the acute rim and broadly 

rounded contour of this end in Neurankylus 

baueri Gilmore. It may be that these peculiarities are due to an injury received in life, 

though the character of the bone appears to be 

normal. The fragmentary nature of the specimen renders it a poor subject for further 

speculation, and its principal interest at this 

time lies in the fact that it somewhat extends 

the known geologic and geographic range of 

the genus. The specimen was collected 32 

miles south of west of Kimbetoh, San Juan 

County, N. Mex., near the south side of sec. 4, 

T. 22 N., R. 10 W., 75 feet above the base of 

the Kirtland formation. 

Genus COMPSEMYS Leidy, 1856. 

Until the acquisition of the specimens here 

described the genus Compsemys has been known 

only from very fragmentary materials. The 

genus was founded by Leidy in 1856 to receive 

the scanty remains which he named Compsemys 

victus. In later years many species have been 

referred to this genus and subsequently removed from it, so that at this time it comprises but six recognized species, and the 

generic assignment of one of these, C. obscura, 

is queried by Hay.1 In the order in which they 

were described, the species are Compsemys 

victa Leidy, C. obscura (Leidy), C. parva Hay, 

C. vafer Hay, C. torrejonensis Gilmore, and C. 

puercensis Gilmore. 

In 1908, from the study of scanty materials, 

Hay 2 was led to believe that a mesoplastron 

was not present in Compsemys, and on that account he provisionally assigned the genus to the 

family Dermatemydidae, but in 19113 the 

study of new material showed the presence of 

semys 

that bone, whereupon Hay transferred 

Washington Pub. 75, p. 235, 1908. 

1 Hay, 0. P., The fossil turtles of North America: Carnegie Inst. 

3 

2 Idem, p. 233. 

Hay, 0. P., Descriptions of eight new species of fossil turtles from 

to the superfamily Amphichelydia, 

Compwest of the one hundredth meridian: U. S. Nat. Mus. Proc., vol. 38, p. 308, 

1911. 

making it a member of the family Baenidae. 

The genus was defined as follows: 

A genus of Baenidae. Plastron relatively small, with 

broad mesoplastra which meet at the raidline. Axillary 

and inguinal buttresses rising above the lower ends of the 

costals; buttresses wide transversely to the body and 

shutting off ample sternal chambers. Peripheral bones 

united to costals by jagged sutures. Neural bones with the 

broader end forward. External surface of all the bones 

ornamented with small circular pustular elevations. 

The short and broadly rounded anterior lobe 

of the plastron; the wide entoplastron; the 

broad mesoplastra, joining extensively at the 

midline; the broadly rounded posterior end of 

carapace without scalloped borders; vertebrals 

broad as compared to their lengths; and costoperipheral sutures above costo-marginal sulcus 

are all characters wherein Compsemys resembles 

Glyptops and Neurankylus, of the Pleurosternidae more nearly than any members of the 

Baenidae, and I therefore now refer the genus 

Compsemys to the Pleurosternidae. The following definition of the genus is proposed: 

A genus of Pleurosternidae. External surfaces of the shell ornamented with small, closeset enameled tubercles; first peripherals meet 

on midline and exclude the nuchal from reaching the anterior margin of the carapace; vertebrals broader than long; first suprapygal absent; inguinal buttresses uniting exclusively 

with the fifth costals; mesoplastrals joining 

broad at midline, often narrowing toward outer 

extremities; costo-marginal sulcus entirely 

below costo-peripheral sutures; gulars reduced; 

humerals meeting narrow at midline; entoplastron wider than long; posterior lobe of 

plastron deeply notched; inframarginals only 

partially on plastron. 

The exclusion of the nuchal from the anterior border of the carapace is an important 

structural feature not before observed, so far 

as I have been able to discover, in any turtle 

living or extinct. This feature, taken in conjunction with the articulation of the inguinal 

buttress exclusively with the fifth costal and 

the absence of the first suprapygal, may by 

some students be considered of more than 

generic value, so that a new subfamily should 

be erected for the reception of this genus. At 

this time, however, I do not subscribe to such 

a view, preferring to consider these features as 
ORDER C EIELONIA. 13 

of generic importance, definitely separating 

Compsemys from the other members of the 

family. 

The following table shows the geologic range 

of the genus and the position of the several 

species: 

Geologic distribution of species of the genus Compsemys. 

Fort Union. Compsemys sp. 

Compsemys torrejonensis 

Torrejon. Gilmore, n. sp. 

Compsemys parva' Hay. 

Basal Eocene. 

Compsemys parva Hay. 

Compsemys vafer Hay. Puerco. Compsemys puercensis Gilmore, n. sp. 

Compsemys? obscura 

Lance. (Leidy). 

Compsemys victa Leidy. 

Upper Creta- Arapahoe. Compsemys victa Leidy. ceous. 

Ojo Alamo. Compsemys sp. 

Judith River. Compsemys sp. 

Compsemys parva Hay. 

Plate I, figures 1 and 2; Plate XIX, figure 3. 

Compsemys parva Hay, U. S. Nat. Mus. Proc., vol. 38, 

pp. 308-310, text fig. 1, pl. 10, figs. 1, 2, 3, 1910. 

In the collection made by J. B. Reeside, jr., 

and party in the San Juan Basin, N. Mex., 4 

miles east of Kimbetoh, in sec. 35, T. 23 N., 

R. 9 W., at a horizon 50 feet above the base of 

the Puerco formation, during the summer of 

1916, was the greater portion of the carapace 

and plastron of a small turtle, here identified 

as pertaining to Compsemys parva Hay, a 

species founded on a fragmentary specimen 

(No. 6548, U. S. N. M.) consisting chiefly of 

portions of the plastron. The discovery of the 

present specimen,, the most perfect individual 

of the species yet found, now makes it possible 

to give an adequate diagnosis and description 

of this species. At the time the species was 

established some doubt was expressed as to 

the exact geologic age of the type, but the 

discovery of this - specimen in undoubted 

Pureco deposits appears to establish its geologic position. 

The specimen (No. 8528, U. S. N. M.) represents an individual that is slightly larger than 

the type specimen, the length of the plastron at 

B 

FIGURE 1.— Compsemys parva Hay (No. 8528, U. S. N. M.). A, Carapace: 

C i, C 8, Costal bones l and 8; N1, 2, 3, 4,5,6,7, 8, neural bones 1 to 

8; nu, nuchal; per 1, first peripheral; py, pygal; spy 2, suprapygal. 

B, Plastron: ab, abdominal scute; an, anal scute; ent, entoplastron; 

epi, epiplastron; fern, femoral scute; g, gular scute; hum, humeral scute; 

hyo, hyoplastron; hypo, hypoplastron; ing, intergular scute; meso, 

mesoplastron; pea, pectoral scute; xiph, xiphiplastron. One-half 

natural size. 

the center being about 130 millimeters, whereas 

Hay estimated the plastron of the type as 

probably not exceeding 120 millimeters. The 
14 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

carapace appears to have been comparatively 

low and broadly arched, probably following the 

general outlines of the shell as expressed by the 

type of C. torrejonensis, though it appears to have 

been more pointed behind. (See Pl. IV.) It 

has a greatest length of about 165 millimeters 

and a greatest breadth of about 120 millimeters. 

All the bones of the carapace and plastron are 

ornamented with low, close-set elevations or 

pustules. (See Pl. I.) These pustules on the 

plastron merge into one another, especially 

along the sutures, thus forming short ridges 

that usually take a fore,and aft direction. On 

the carapace two and three of these pustules 

often join, forming short bent ridges that do 

not assume any regular direction. All the 

pustules and ridges on both carapace and 

plastron are flat topped. There are from six 

to seven of these in a line 5 millimeters long. 

In C. victa, as Hay has pointed out, " there is 

the same number of pustules in a 5-millimeter 

line, but they seem to have more pointed summits, and the intervening valleys are wider." 

In C. vafer, except along the borders of the 

carapace and plastron, the sculpture appears 

to be less clearly defined than in the other 

species mentioned above. 

The nuchal bone is subquadrilateral, with the 

broadest side joining the first and second peripherals. It measures about 34 millimeters in 

greatest width. In calling this bone the nuchal 

I interpret the paired elements which immediately precede it and which form the median 

border as the first peripherals. (See fig. 1, A, 

per 1.) If a single median element were present, I would then designate it the nuchal and 

the larger element here called nuchal the preneural, thus following Hay 1 in this interpretation of these elements in Chisternon. A preneural is also present in Boremys, another 

member of the Baenidae, though absent in all 

other genera of the family. This bone is also 

present, but much reduced, in Aspideretes and 

Plastomenus. 

The first neural is oval; the six following are 

hexagonal, with the wider end forward; the 

eighth has the wider end posterior. All except 

the first are wider than long. The anterior 

ends of the second and third are concave; all 

others join by straight transverse sutures. 

1 Hay, 0. P., The fossil turtles of North America: Carnegie Inst. 

Washington Pub. 75, p. 57, 1908. 

Measurements of the neurals of Compsemys parva (No. 

8528, U. S. N. M.), in millimeters. 

No. Length. Width. 

1 15 11. 5 

2 13 15 

3 14.5 15 

4 12.5 15 

5 12.5 15 

6 9 15 

7 11 13 

8 13.5 14 

The pygal is missing. 

The peripherals in this specimen are represented by the first, seventh, eighth, and tenth 

of the right side, the seventh, eleventh, and 

part of the first of the left side, and fragmentary 

parts of others whose exact position in the 

series has not been recognized. The first peripherals of opposite sides meet on the median 

line. The first is 14 millimeters long on the 

free border and has a greatest height of 11.5 

millimeters; the seventh is 22 millimeters long; 

the eighth 21 millimeters; the eleventh is 16 

millimeters long and has a depth of 21 millimeters. The free borders of the peripherals 

are subacute. 

The costals grow successively narrower from 

the front toward the back. Their distal ends 

articulate with the peripherals by means of 

dentated sutures. On the inferior surface of 

the first costal is a rounded ridge produced by 

the strongly developed rib, which forms an 

articulation with the axillary buttress. The 

buttress, as in the type, rises about 10 millimeters above the lower border of this costal. 

The articulation for the inguinal buttress is entirely on the fifth costal and rises about 5 millimeters above the lower border of that bone. 

The costals of this specimen are relatively 

thinner than those of the few preserved with 

the type specimen. 

The nuchal scute, as in C. vafer Hay, is small, 

narrow anteroposteriorly, and elongated transversely, being about 10 millimeters wide and 2 

millimeters long at the center. 

The vertebra's, except the first, are wider 

than long. In this specimen the fourth vertebral has a decided loop extending forward into 

the third vertebral on the midline. All these 

scutes are broader in front than behind. There 

is only slight expansion on the sides where the 
ORDER CHELONIA. 15 

costal sulci are given off. The fourth is urnshaped. 

Measurements of vertebrals of Compsemys parva (No. 8528, 

U.S. N.M.), in millimeters. 

No. Length. Width. 

1 36 50 

2. 29 41 

3 29 43 

4 30 36 

The costal scutes are of moderate size. The 

second is the widest; the third has a length of 

30 millimeters and a height of 40 millimeters. 

All extend slightly below the costo-peripheral 

suture. 

The posterior marginals in Compsemys parva 

extend high on the peripherals as compared 

with those of the other species of the genus; for 

example, the eleventh peripheral shows the 

sulcus within 4 millimeters of the costoperipheral suture, whereas in the type of C. 

torrejonensis it is 19 millimeters from the top 

of the same bone; or, in other words, in C. 

torrejonensis and apparently also in C. vafer the 

costomarginal sulcus crosses the peripherals at 

about their centers or below. The great 

height of the posterior marginals therefore 

appears to be one of the distinctive characters 

of this species. 

The plastron has a length at the center of 

about 30 millimeters, and a greatest length of 

about 135 millimeters; the difference between 

these measurements (5 millimeters) represents 

the depth of the posterior notch. The plastron 

is relatively thinner than in the type of the 

species, and the sulci, though plain, are not so 

deeply impressed. Only a small portion of 

the border of the anterior lobe on the right 

and left sides is preserved, but this shows it to 

be without thickening and rather obtusely 

rounded. There does not appear to have been 

an epiplastral lip. 

The entoplastron is about 28 millimeters 

wide and, as in Compsemys vafer Hay (No. 

8529, U. S. N. M.), appears to have been wider 

than long. It is estimated that the bridge 

had a width of about 60 millimeters, being 

therefore nearly one-half the entire length of 

the plastron. 

The posterior lobe has a length of about 42 

millimeters and a width of 63 millimeters. It 

is sharply notched at the center. The borders 

are thin and present sharp edges—in fact, the 

entire posterior two-thirds of this lobe is 

unusually thin. 

The axillary and inguinal buttresses. are of 

moderate development, are wide apart, and 

unite with the carapace by strongly developed 

sutures. The right hyoplastron is somewhat 

longer (antero-posteriorly) than the left, the 

former measuring 26 millimeters on the midline and the latter only 20 millimeters. The 

right hyoplastron thus came into contact with 

the inner end of the left mesoplastron. The 

mesoplastra, likewise, differ considerably in 

length at the center (see fig. 1, B, meso), the 

left being 27 millimeters long and the right 19 

millimeters. The left mesoplastron is in contact with the inner ends of both the hyoplastron and hypoplastron of the right side. Hay 

considered that the same conditions prevailed 

in the plastron of the type. The mesoplastron 

at the center has a thickness of 6.5 millimeters, 

as compared with 6 millimeters in the type, a 

smaller specimen. The hypoplastra also differ 

in length at the center, the right measuring 29 

millimeters and the left 26 millimeters. The 

xiphiplastrals are of equal length, measuring 

26 millimeters long on the midline. 

The sulci bounding the epidermal scutes are 

very distinct and consist of threadlike grooves 

on the level of the general surface. The median 

sulcus runs an irregular course, being first on 

one side of the midline and then on the other. 

The intergulars overlap the anterior end of 

the entoplastron, and it is estimated that they 

met on the midline for a distance of at least 

17 millimeters. The gulars, as in Compsemys 

vafer, are small and are excluded from meeting 

on the midline by the intervening intergulars. 

The humero-pectoral sulcus starts from the 

axillary notch strongly forward to cross the 

entoplastron 8 millimeters anterior to its 

median posterior extremity, and in this respect 

Compsemys parva differs from all other members of the Baenidae as well as all Pleurosternidae. The humerals join on the midline for a 

distance of only 5 millimeters, but, as in 

Basilemys sinuosa Riggs, they expand rapidly 

toward their outer ends. The pectoral scutes 

are exceedingly broad at the midline and are 

41 millimeters long; their outer ends measure 

less than 30 millimeters; the abdominals join 
16 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

on the midline, a distance of 31 millimeters; 

the femorals are narrow at the center, meeting 

for only 10 millimeters, but they expand 

rapidly toward their outer ends, there reaching a greatest length of 30 millimeters. The 

anals meet for 24 millimeters on the midlineOn account of the damaged condition of the 

bridges the number of inframarginal scutes 

can not be determined. 

A second specimen in this collection (No. 

8598, U. S. N. M.) is provisionally identified as 

belonging to the present species. It consists of 

a considerable part of the plastron, neurals 2 

and 3, costals, peripheral (see Pl. XIX, fig. 3), 

and numerous other fragmentary bones of the 

carapace. It was collected 8 miles N. 60° E. 

of Kimbetoh, in sec. 17, T. 23 N., R. 8 W., 

San Juan County, N. Mex., at a horizon 840 

feet above the base of the Puerco, in the 

Torrejon. formation. This specimen is an 

individual slightly larger than the type of C. 

parva, and the plastral bones appear to be a 

little thicker than the Puerco specimen (No. 

8528) above described. I have carefully compared this specimen with both the type and 

No. 8528 and fail to detect characters that 

would serve to distinguish it from them. I 

therefore propose to refer it provisionally to the 

present species until such time as the discovery 

of new material shall definitely determine its 

exact affinities. The anterior lobe is 37 millimeters long and 67 millimeters wide at the 

base. The entoplastron is 27 millimeters wide 

and 23 millimeters fore and aft. It is overlapped by the intergulars in front and the 

pectorals behind. The hyoplastrals meet on 

the midline for 117 millimeters. The mesoplastron of the left side is 24 millimeters wide, 

on the right side only 14 millimeters wide. 

The bridge is 58 millimeters wide. The posterior lobe is about 60 millimeters wide at the 

base. The intergulars meet on the midline for 

19 millimeters, the hum erals for 6 millimeters, 

the pectorals for 34 millimeters, and the abdominals for about 33 millimeters. The second 

neural is 14 millimeters long and 16 millimeters wide; the third about 15 millimeters 

long and 14 millimeters wide. The second 

vertebral scute has a greatest width of 42 

millimeters. 

The characters that now appear to definitely distinguish Compsemys parva Hay from 

the other species of the genus may be briefly 

stated as follows: 

Specific characters: Small size; costo-marginal sulcus crossing peripherals of posterior 

half of carapace, on their upper fourths, 

whereas in all other species it crosses them 

midway or below; posterior lobe of plastron 

with a median V-shaped notch; eighth neural 

relatively large. 

Compsemys vafer Hay. 

Plate II, figures 1 and 2. 

Compsemys vafer Hay, U. S. Nat. Mus. Proc., vol. 38, pp. 

311-313, text. figs. 2-5, pl. 10, figs. 4 and 5; pl. 11, 

figs. 1 and 2, 1910. 

This species was founded on a fragmentary 

specimen (No. 6551, U. S. N. M.) consisting of 

"about nine peripherals, three neurals, a few 

fragments of costal plates, and some fragments of the plastron." It was collected from 

the Puerco formation near Ojo Alamo, San 

Juan County, N. Mex. 

The present collection contains three specimens (Nos. 8529, 8530, and 8600, U. S. N. M.) 

that are identified as belonging to this species. 

The best specimen (No. 8529) consists of the 

greater part of the plastron and a considerable 

portion of the carapace. It is by far the most 

perfect specimen of this species yet found and 

adds materially to our knowledge of this little 

known form. 

This specimen .Ls an individual of approximately the same size as the type of the species. 

The carapace as now preserved consists largely 

of the median portion of the shell from which 

all parts posterior to the eighth neural and the 

distal thirds of many of the costals are missing. 

On the left side the third, fourth, and fifth 

costals and the seventh and eighth peripherals 

are present. The nuchal is missing, but the 

bones bounding it give its approximate shape 

and size as shown in figure 2, A, mu. A little 

more than one-half of the anterior border of 

the shell is intact and shows it to be broadly 

concave when viewed from above as contrasted with the straight, truncated border of 

Compsemys torrejonensis. Hay, in discussing 

the type of the species, estimated that "the 

carapace had originally a length of about 

1 foot." No. 8529, which is of about the same 

size as the type specimen, would be somewhat 

under a foot in length. 
ORDER CHELONIA. 17 Aftlior 

,
 11 

Aral11114 issemotior alit* 

FIGURE 2.—Compsemys vafer Hay (No. 8529, U. S. N. M.). A, Carapace: C I, C 7, C 8, Costal bones 1, 7, and 8; N 1,2,3, 4, 6, 6,7,8, neural bones 

1 to 8; nu, nuchal; per 1, per 3, peripherals 1 and 3. B, Plastron: ab, Abdominal scute; an, anal scute; ent, entoplastron; epi, epiplastron; 

fern, femoral scute; g, gular scute; hum, humeral scute; hyo, hyoplastron; hypo, hypoplastron; ing, intergular scute; in. mar, inframarginal 

scutes; meso, mesoplastron; pec, pectoral scute; xiph, xiphiplastron. One-half natural size. 

The neurals are all perfectly preserved 

except the eighth, which lacks its posterior 

extremity. The first is oval; those following 

are hexagonal, with the broader end forward. 

All except the first are broader than long. 

Their form is well shown in figure 2, and their 

dimensions as compared with those of the type 

are given in the following table: 

Measurements of neurals in Compsemys wafer, in millimeters. 

Length Width. 

No. 

No. 6551 

(tYPe). No. 8529. No . 

6551 

(tYpe). No . 

8529. 

1 25 23 19 19 

2 21 22 24 23 

3 22 22 24 23 

4 20 25 

5 18 26 

6 11 26.5 

7 15 22 

3 15 

The costals fore and aft grow progressively 

narrower from the first to the seventh. The 

115836°--19----2 

seventh is relatively very much smaller in all 

dimensions than the corresponding element in 

the type of Compsemys torrejonensis (see fig. 4), 

which measures 21 millimeters in width and 

has a greatest length of 50 millimeters. Hay 1 

figured a peripheral which he identified as the 

first, but a comparison with the present articulated specimen shows this bone to be the right 

second peripheral. 

The first peripherals meet on the median 

line and thus exclude the nuchal plate from 

reaching the front margin. The first peripheral has a width on the free margin of 21 millimeters, the second 33 millimeters, and the 

third 39 millimeters; the height of the third 

is 33 millimeters. The anterior border is 

obtusely rounded. On the lower side the 

sculptured surface extends backward from the 

edge 9 millimeters at the center where the first 

peripherals join, but this surface gradually 

widens away from the center, and at the outer 

end of the third peripheral it is 18 millimeters 

I Hay, 0. P., Descriptions of eight new species of fqssil turtles from 

west of the one hundredth meridian: U. S. Nat. MuS. Proc., vol. 38, 

p. 311, pl. 10, fig. 5, 1910. 
18 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

wide. The seventh and eighth peripherals of 

the left side have a length on free borders of 

36 and 38 millimeters and a height of 38 and 

43 millimeters, respectively. The free borders 

of these peripherals are obtusely rounded, but 

more posteriorly, as shown by the peripherals 

of the type specimen, the edge becomes 

subacute. 

The nuchal scute is very short (3 millimeters) fore and aft, but wide transversely, as 

in the other species of the genus. 

Measurements of vertebral scutes in Compsemys vafer (No. 

8.529, U. S. N. AL), in millimeters. 

GreatNo. Length. est 

width. 

1 57 75 

2 46 61 

3. 42 64 

4 43 50 

5 

As is shown in figure 2, A, the marginal scutes 

run low down on the peripherals, well below 

the costo-peripheral suture, as in Compsemys 

torrejonensis. 

The external surfaces of all the bones are 

ornamented by flat-topped pustules without 

definite pattern or arrangement. As Hay has 

already pointed out, there are usually seven of 

these pustules in a line 5 millimeters long. 

The plastron has a length at the center of 

203 millimeters. The anterior lobe is about 59 

millimeters long; its width at the base is 105 

millimeters. The edges are slightly thickened 

and rounded. In shape the entoplastron is 

roughly hexagonal, 45 millimeters wide and 35 

millimeters long. The hyoplastra meet on the 

midline for 24 millimeters. The mesoplastra, 

as in Compsemys parva and C. torrejonensis, 

differ in their fore and aft width at the midline, 

where the right element is 24 millimeters wide 

and the left 45 millimeters. The latter narrows 

toward its outer end, which is only 30 millimeters in this diameter. The median end 

meets in succession the hyoplastral, mesoplastral, and hypoplastral bones. 

The posterior lobe has a greatest length of 

68 millimeters; at the center its length is 56 

millimeters. The difference between these 

measurements (12 millimeters) represents the 

depth of the very wide posterior notch. The 

width of this lobe at its base is about 92 millimeters. The edges are thickened and rounded 

as contrasted with the acutely edged borders 

in Compsemys parva or with the obtusely 

beveled borders in 

notch has a greatest width of 40 millimeters. 

developed xiphiplastral processes the posterior 

Between these processes the median border 

jonensis. Between the tips of the prominently 

C. puercensis and C. torrepresents a straight, sharp edge 22 millimeters 

long. The shape of this notch is quite distinctive of this species, when contrasted with 

the V-shaped notch of C. parva or the deep 

U-shaped notch of C. torrejonensis. (See fig. 4.) 

The bridge has a width of 86 millimeters. 

The hypoplastrals meet on the midline for 38 

millimeters; the xiphiplastrals for 41 millimeters. The plastron is somewhat concave, 

apparently indicating the male sex of the individual. 

The gulars are small and crowded far from 

meeting on the midline by the large triangular 

intergulars, which overlap the forward end of 

the entoplastron. The intergulars meet on the 

midline for 30 millimeters, the humerals for 6 

millimeters, the pectorals for 62 millimeters, 

the abdominals for 44 millimeters, the femorals 

for 30 millimeters, and the anals for 30 millimeters. 

There are four inframarginal scutes on the 

bridge. 

Compsemys vafer can now be distinguished 

from C. torrejonensis by the different form of 

the posterior notch of the plastron, by the 

rounded margins of the posterior lobe as contrasted with the beveled lobe of C. torrejonensis, 

by the broadly concave contour of the anterior 

border of the carapace, by the relatively 

smaller seventh costal, and by differences in 

the ornamentation of the carapace and plastron. 

In the sculpture Compsemys vafer also differs 

from both C. parva and C. victor. From C. 

parva it is also to be distinguished by the 

larger size and differences in the hinder lobe, 

especially in the form of the notch and the more 

rounded free edges, as contrasted with the 

U-shaped notch and acutely beveled edges of 

that species. 

The distinguishing characters of Compsemys 

vafer may be summed up as follows: 

Specific characters: Medium size; costo-marginal sulci crossing posterior peripherals at 
ORDER CHELONIA. 19 

middle of their height or below; sulcus between 

third and fourth vertebrals crossing fifth neural; posterior lobe of plastron with a wide 

median notch and prominently developed 

xiphiplastral processes. 

Compsemys puercensis Gilmore, n. sp. 

Plate III, figures 1 and 2. 

Type: No. 8544, U. S. N. M.; consists of posterior two-thirds of plastron, first six neurals, 

with portions of attached costals, and various 

fragments. Collected by J. B. Reeside, jr., 

1916. 

species, and I therefore propose the name C. 

puercensis for this specimen in reference to the 

geologic formation in which it was discovered. 

The characters which at present distinguish 

this species are found in the posterior lobe of 

the plastron, especially those relating to its 

contour, the form of the posterior notch, and 

the absence of xiphiplastral procbsses. Other 

minor differences will be referred to in the 

descriptions. 

The ornamentation of both carapace and 

plastron is composed of flat-topped pustules 

as in Compsemys vafir and C. torrejonensis and 

A B 

FIGURE 3.—Compsemys puercensis Gilmore, n. sp. (No. 8544, U. S. N. M.). A, Carapace: C 1, C6, Costal bones 1 and 6; N i, 2, 3, 4, 5, 6, neural 

bones 1 to 6; nu, nuchal; per I, per 2, peripherals 1 and 2. B, Plastron: ab, Abdominal scute; an, analscute; ent, entoplastron; epi, epiplastron; 

fern, femoralscute;g, gular scute; hum, humeral scute; hyo, hyoplastron; hypd, hypoplastron; in mar, inframarginal scute; ing, intergular scute; 

mesa, mesoplastron; pet, pectoral scute; xiph, xiphiplastron. One-half natural size. 

Type locality: Four miles northwest of 

Kimbetoh, on the north line of sec. 27, T. 23 

N., R. 9 W., San Juan County, N. Mex. 

Horizon: Puerco formation (50 feet above 

the base), basal Eocene. 

shows characters in the plaaron which appear 

semys puercensis, 

to distinguish it fully from the other described 

The specimen selected aq, the type of 

although rather fragmentary, 

Compapparently C. puercensis is indistinguishable 

from those species in the general composition 

of this sculpture. 

The individual is smaller than specimen No. 

8529, U. S. N. M., referred to C. vafer, the 

length of the plastron having probably not 

exceeded 195 millimeters, whereas that of No. 

8529 measures 218 millimeters. Both xiphiplastra, the right hypoplastron, portions of 
20 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

both mesoplastra, and a part each of the right 

and left hyoplastron and of the epiplastral 

bones are present. (See fig. 3, B.) 

The posterior lobe has a length at the center 

of 50 millimeters and a greatest length of 60 

millimeters; the difference represents the depth 

of the wide median notch. From the inguinal 

notch backward the free borders present subrounded edges that in cross section are about 

intermediate in form between the acute edges 

of C. torrejonensis and the rounded edges of 

C. vafer. The lobe is widest (86 millimeters) 

at its base, the sides of which gradually round 

in toward the notch on the posterior end, 

whereas in the two species mentioned above 

the greatest width of the posterior lobe is 

FIGURE 4.—Comparative view of the posterior lobes of the plastra 

of four species of Compsemys. A, Compsemys torrejonensis Gilmore, n. 

sp. (type; No. 8549 U. S. N. M.); B, C. puercensis Gilmore, n. sp. (type; 

No. 8544, U. S. N. M.); C, C. parva Hay (No. 8528, U. S. N. M.); D, C. 

vafer Hay (No. 8529, U. S. N. M.). 

posterior to the inguinal notch. The broad 

posterior notch is 10 millimeters deep and 33 

millimeters wide between the tips of the xiphiplastral processes. The shape of this notch 

is also of assistance in distinguishing 

is shown in figure 4. 

censis 

on the midline of 32 millimeters and a thickThe right mesoplastron has a greatest length 

from the other species of the genus, as 

C. puerness at the center of 7.5 millimeters; the right 

hypoplastron is 33 millimeters long on the 

midline; the xiphiplastrals vary in their length 

at the center, the left one measuring 38 millimeters and the right only 33 millimeters. 

The median sulcus, as is usual in this genus, 

runs a very irregular course. The femorals 

meet on the midline for a distance of 28 millimeters; the anals for 25 millimeters. 

The parts of the carapace preserved with 

this specimen are so fragmentary as to be of 

comparatively little value in furnishing any 

distinctive features of the species. 

The largest articulated portion consists of 

neurals 1 to 6, with portions of attached costals, of which only the fifth of the right side is 

complete. This costal shows, however, that 

the main attachment with the inguinal buttress 

was entirely with this bone. 

The neurals, except the first, are hexagonal, 

with the widest end directed forward. 

Measurements of neurals in Compsemys puercensis (No. 8544, 

U. S. N. M.), in millimeters. 

No. Length. Width. 

1 16 

2 '20 22 

3 23 22 

4 20 23. 5 

5 17.5 25 

6 13 26 

In shape and proportions the neurals are 

very close to those of C. vafer. 

The second peripheral of the right side has a 

width on the free border of 27 millimeters and 

a height of 27 millimeters; a portion of the left 

peripheral is present, and these two pieces constitute all that is known of the rim of the carapace at the present time. 

The fifth costal has a greatest length of 70 

millimeters. It is 19 millimeters wide at the 

proximal end and 27 millimeters wide at the 

distal end. 

The dimensions of the vertebral scutes, so 

far as they can be determined, are as follows: 

Measurements of vertebrals in Compsemys puercensis (No. 

8544, U. S. N. M.), in millimeters. 

No. Length. Width. 

2 45 54 

3. 42 48 

4 51 

These scutes are relatively narrower than in 

C. vafer. 
ORDER CHELONIA. 21 

Specific characters: Medium size; sulcus between third and fourth vertebrals crosses fifth 

neural, as in C. vafer; posterior lobe of plastron 

with wide median V-shaped notch, and without 

prominent xiphiplastral processes. 

Compsemys torrejonensis Gilmore, n. sp. 

Plate IV, figures 1 and 2. 

Type: No. 8549, U. S. N. M.; consists of a 

nearly complete carapace and plastron. The 

principal parts missing are the posterior neurals 

and the median peripherals of both sides. 

Collected by J. B. Reeside, jr., 1916. 

representative of this genus to be found in the 

Torrej on formation. The specific name given to 

it refers to the geologic occurrence of the type. 

In form the shell is an elongated oval, 

broadest behind the middle, truncated in front, 

broadly rounded behind. (See Pl. IV, figs. 1 

and 2, and text fig. 5.) From side to side the 

carapace isiflattened, with a long slope from the 

top to the posterior margin. In front the forward slope of the carapace is much shorter and 

the downward inclination much less. Viewed 

from the side the shell is high in front and low 

behind (see fig. 6), with a strongly arched anA B 

FIGURE 5.—Compsemys torrejonensis Gilmore, n. sp. (No. 8549, U. S. N. M.). Type. A, Carapace: C i, C 8, Costal bones 1 and 8; N14,8,4,5,6,7, 

8, neural bones 1 to 8; nu, nuchal; per 1, per 11, peripherals 1 and 11; py, pygal; spy 2, suprapygal 2. B, Plastron: ab, Abdominal scute; an, 

anal scute; ent, entoplastron; epi, epiplastron; fern, femoral scute; g, gular scute; hum, humeral scute; hyo, hyoplastron; hypo, hypoplastron; ing, intergular scute; mesa, mesoplastron; pee, pectoral scute; xiph, xiphiplastron. One-fourth natural size. 

Type locality: Eight miles N. 60° E. of 

Kimbetoh, in sec. 17, T. 23 N., R. 8 W., San 

Juan County, N. Mex. 

Horizon: Torrej on formation (" 840 feet 

above base of the Puerco, in Torrejon"), basal 

Eocene. 

fragments, but in the skillful hands of Mr. N. H. 

semys torrejonensis 

of the genus 

found, the shell was broken into many small 

The specimen selected as the type of 

Compsemys 

is the most perfect example 

yet discovered. When 

CompBoss, preparator in the section of vertebrate 

paleontology, these pieces were fitted together 

so as to restore the nearly complete shell with 

all its contours and proportions but little altered from their original condition. In addition to being the most perfect specimen of the 

genus known at this time it is also the first 

terior border, thus forming a very large opening for the head and fore legs as contrasted 

with the comparatively small openings for the 

hind legs. 

As in Compsemys vafer the external surfaces 

of all the bones forming the carapace and plastron are covered with an ornamentation of pustules. These pustules are flat topped and are 

separated by narrow intervening valleys. On 

many of the bones, especially the peripherals 

and costals, these pustules form two, three, or 

even four parallel rows around the borders of 

the bones. This feature is best shown in a'second 

specimen (No. 8591, U. S. N. M.) collected at 

the same time and in the same locality as the 

type. On the pla'stron the pustules are to a 

great extent arranged in rows running longitudinally to the long axis of the shell. This 
22 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

arrangement of the pustules will serve to distinguish the plastron of this species from that 

of C. vafer Hay and C. puercensis in which the 

pustules have no definite arrangement. 

The greatest length of the carapace in a 

straight line is 280 millimeters; the greatest 

width, which is posterior to the middle, is 208 

millimeters; the greatest height is about 82 

millimeters. 

Posterior to the first their distal ends are 

pointed and unite closely with the peripherals 

by jagged sutures. There are, as in most 

turtles, 11 peripheral bones. Peripheral 1 is 

entirely in front of the nuchal. It meets its 

fellow of the opposite side on the midline and is 

entirely excluded from contact with the first 

costal. In form it is square, measuring 23 

millimeters long and 23 millimeters wide. The 

FIGURE 6.—Lateral view of the shell of Compsemys torrejonensis Cilmore, n. sp. (No. 8549, U. S. N. M.). Type. One-half natural size. 

The nuchal bone is 45 millimeters wide on 

the front border; but the bone has a greatest 

width of 59 millimeters; its greatest length is 

37 millimeters. As in other members of the 

genus, its anterior border is excluded from the 

rim of the carapace by the first peripherals, 

which join on the median line. In all probability there were eight neurals, but in the type 

specimen only the first, second, fourth, and 

fifth are present. The first is oval; the others 

are hexagonal, with the wider end in front. 

Measurements of neurals in Comvsemys torrejonensis (No. 

8549, U. S. N. M.), in millimeters. 

GreatNo. Length. est 

width. 

1 25 18 

2 23 24 

3 a 26 a 22 

4 20 24 

5 18 26 

a Estimated. 

Apparently there was but a single suprapygal 

(probably suprapygal 2), and only a small portion of the right side of this element is preserved. It had a greatest width of about 58 

millimeters; its length can not be determined. 

Antero-posteriorly the costals become successively narrowed from the first to the eighth. 

free border is obtusely rounded. The height 

of the peripherals, at right angles to the border, 

gradually increases from the first to the sixth. 

The seventh to the tenth in this dimension 

remain subequal, but the eleventh is shorter. 

The pygal is deeply but narrowly notched on 

the midline. It measures 26 millimeters along 

the free edge and is 35 millimeters high. The 

free border is acutely edged. The costoperipheral sutures are everywhere well above 

the costo-marginal sulcus. 

The sulci are narrow and shallowly impressed, 

but nearly all are clearly defined. The nuchal 

scute is small and rectangular; the longer diameter is transverse. Its length, antero-posteriorly is 6 millimeters; its width 19 millimeters. There are slight indentations of the 

border at either end of this scute where the 

sulci come to the margin. 

The vertical scutes are broad. 

Measurements of vertebral scutes in Compsemys torrejonensis 

(No. 8549, U. S. N. M.), in millimeters. 

Greatest No. Length. width. 

1. 66 82 

2 54 63 

3 54 61 

4 49 

5 73 
ORDER CHELONIA. 23 

The marginal scutes are relatively narrow 

throughout thp series, and none come anywhere near reaching the costo-peripheral suture, 

which is above. There appear to be 11 marginal scutes. The costal scutes, on account of 

the shortness of the marginals, are of good size. 

The plastron posterior to the center is 

slightly concave and suggests that this specimen is a male. It has a greatest length at the 

center of 220 millimeters and a greatest length 

over all of 246 millimeters. The difference between these measurements, 26 millimeters, represents the depth of the notch on the posterior 

lobe. The front lobe is comparatively short, 

is broadly rounded, and extends forward even 

with the anterior border of the carapace. (See 

Pl. IV, fig. 2.) The anterior lobe is 57 millimeters long; its width at the base is 117 millimeters. The edges are obtusely rounded, 

being beveled off from the upper surface 

downward. The entoplastron is about 34 

millimeters long, 52 millimeters wide, and 

angularly rounded behind. The hyoplastrals 

meet at the midline for about 32 millimeters; 

the right element is much longer antero-posteriorly and thus is in contact with the mesoplastron of the left side for a distance of 20 

millimeters. The mesoplastra also differ in 

width antero-posteriorly, the right measuring 

27 millimeters and the left 46 millimeters. 

Both narrow away from the center, but more 

especially the left, which at the edge of the 

plastron is only 34 millimeters fore and aft. 

In the shape and relative proportions of these 

elements they approach those of Glyptops 

depressus Hay, from the Denver formation. 

The hypoplastrals meet on the midline for 41 

millimeters. The right element also meets the 

left mesoplastron. The xiphiplastrals have a 

contact at the center of 96 millimeters. 

The posterior lobe at the center is 65 milli_ 

meters long and 112 millimeters wide at the 

base. The free borders are acutely edged, but 

the bone thickens from the borders inward, 

reaching its maximum thickness (9 millimeters) 

about 15 millimeters in from the border. The 

lateral borders swell outward slightly from the 

inguinal notch posteriorly, but back of the 

hypo-xiphiplastral suture curve inward and 

still more rapidly at the femoro-anal sulcus. 

The posterior end of the plastron is deeply 

indented by a large U-shaped notch, 26 millimeters deep and 40 millimeters wide. The 

posterior extremities of the plastron end about 

28 millimeters anterior to the posterior margin 

of the carapace. The bridge has a width of 113 

millimeters on the right side but measures only 

96 millimeters on the left, and there is no apparent distortion or injury. The plastron at the 

center of the bridge measures 144 millimeters 

in width. 

Strong buttresses rise to the costals; the 

axillary buttress unites with the underside of 

the first costal, the inguinal entirely with the 

fifth costal. Both are attached low down. 

Nearly all the sulci bounding the epidermal 

scutes can be clearly determined. As in the 

other members of the genus, the median 

sulcus, so far as it can be traced, runs a very 

irregular course. The gulars are very small 

and are excluded by the interposition of the 

large intergulars from meeting on the midline. 

(See fig. 5, B.) The intergulars overlap the 

anterior end of the entoplastron and meet on 

the middle for 35 millimeters. The humeropectoral sulcus extends diagonally forward 

from a point posterior to the axillary notch 

and meets its fellow of the opposite side well 

forward on the entoplastron. The humerals 

are thus made very narrow where they meet 

on the midline, in this specimen only 7 millimeters. The pectorals meet on the midline 

for a distance of 72 millimeters; the abdominals for 52 millimeters; the femorals for 35 

millimeters; the anals for 18 millimeters. 

The area of the left abdominal is not more 

than half that of the right. There are four 

large inframarginal scutes on the bridge, 

which are remarkable for their inward extension toward the center of the shell. Their 

inner borders are mesiad of a line drawn connecting the lateral borders of the base of the 

anterior and posterior lobes. This condition 

is approached in Glyptops, but in all members 

of the Baenidae the inner borders are far 

outside of such a line. In the family Pleurosternidae the mesiad encroachment of the 

inframarginals on the pectorals and abdominals 

appears to be peculiar to the genus Compsemys, 

and in C. torrejonensis the inframarginals appear to have reached their maximum development. 

Compsemys torrejonensis appears to have its 

closest affinities with C. vafer Hay from the 

underlying Puerco formation. It may be distinguished from that species by the relatively 
24 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

wider posterior lobe, the deeper U-shaped 

notch of the plastron (see fig. 4, p. 20), and the 

acuteness of the free borders of the posterior 

lobe. The squarely truncated end of the carapace will also serve to distinguish these species, 

as in C. vafer this border is broadly concave. 

The differences in the character of the ornamentation, as has previously been pointed out, 

will also help in their differentiation. This 

sculpture also differs from that of both C. 

victa Leidy and C. parva Hay. The much 

smaller size of C. parva would at once distinguish it from C. torrejonensis. 

Specific characters: Typically largest known 

species; costo-marginal sulcus crossing all peripherals at middle of their height or below; 

sulcus between vertebrals 3 and 4 crossing 

sixth neural; posterior lobe of plastron with a 

deep U-shaped median notch; xiphiplastral 

processes prominently developed; eighth costal 

plate relatively small. 

Family BAENIDAE Cope. 

The family Baenidae is represented in the 

present collection by specimens pertaining to 

the genus Baena. The geologic occurrence of 

the family is here extended into the Puerco 

formation. 

Genus BAENA Leidy, 1870. 

Baena nodosa Gilmore. 

Baena nodosa Gilmore, U. S. Geol. Survey Prof. Paper 98, 

pp. 293-295, p. 76, text figures 34, 35, 1916. 

Since Baena, nodosa was first described, in 

December, 1916, four additional specimens 

pertaining to it have been recognized. These 

somewhat extended the known geologic range 

and the geographic distribution of the species. 

All are fragmentary. The better-preserved 

specimens (Nos. 8603 and 8622, U. S. N. M.), 

consisting of portions of the median part of 

the carapace, were collected in 1916, by J. B. 

Reeside, jr., No. 8603, U. S. N. M., about 2 

miles south of west of Kimbetoh, in sec. 3, 

T. 22 N., R. 10 W., San Juan County, N. Mex., 

300 feet above the base of the Kirtland formation, and No. 8622, U. S. N. M., about 5 

miles south of Kimbetoh, in sec. 26, T. 22 N., 

R. 10 W., 50 feet above the base of the Fruitland formation. The type is from the Kirtland formation. 

A third specimen is recognized among a few 

fragments collected by Messrs. Gardner and 

Gidley during the summer of 1909 in the 

vicinity of Ojo Alamo, San Juan County, 

N. Mex. These fragments of the carapace show 

the characteristic nodelike ornamentation of 

the shell, which is so distinctive of this species. 

A fourth specimen, collected by Mr. Reeside, 

31 miles south of west of Kimbetoh, in sec. 4, 

T. 22 N., R. 10 W., 55 feet above the base of 

the Kirtland formation, consists of a great 

number of fragments, but these show the 

characteristic nodelike ornamentation of the 

shell, and it doubtless pertains to the present 

species. Baena sp. undet. 

In this collection are parts of five individuals 

which are referable to the genus Baena but 

none of which are sufficiently well preserved 

to be identified specifically. Two of these, 

consisting of the anterior portions of the 

plastra, probably represent undescribed species, 

but the material is so scanty that I do not feel 

justified in naming them. Both come from the 

same locality (31 miles south of west of Kimbetoh, N. Mex., near the south side of sec. 4, T. 

22 N., R. 10 W.) and from the same horizon 

(75 feet above the base of the Kirtland). 

The better-preserved specimen (No. 8614, 

U. S. N. M.) is distinguished from Baena 

nodosa Gilmore, which it most nearly resembles 

by the broader, more evenly rounded anterior 

end of the anterior lobe; gulars meeting 

broadly on the median line; and on the upper 

side a broad, shallow depression near the 

anterior border. The borders of the lobe are 

also more acute than in Baena nodosa Gilmore. 

The second specimen (No. 8623, U. S. N. M.) 

has an anterior lobe resembling somewhat that 

of Baena escavada Hay, of the Torrejon, 

though the inflation of this lobe in front of the 

humero-gular sulcus is not so pronounced as 

in the type. It differs from No. 8614, U. S. N. 

M., in having a smooth ventral surface, as 

contrasted with the lumpy irregular surface 

of the other specimen. A third specimen 

(No. 8624, U. S. N. M.) from the same locality 

and horizon, consisting of the left half of the 

plastron, may belong to the same species. 

Two other specimens, though exceedingly 

fragmentary, are recognizable as representing 

baenid turtles. Both were collected by Messrs. 

Reeside and Clark—one at a horizon "50 feet 

above the base of the Puerco," 4 miles west of 

Kimbetoh, in sec. 35, T. 23 N., R. 9 W.; the 

other, 4 miles northwest of Kimbetoh, on the 

north line of sec. 27, T. 23 N., R. 9 W. These 
ORDER CRELONIA. 95 

two specimens are of interest at this time only 

as recording the occurrence of the genus 

Baena in the Puerco formation—a not unexpected discovery, for the genus has a range, 

shown by many species, from the Judith River 

up to the top of the Uinta (Eocene). 

Family DERMATEMYDIDAE Gray. 

The family Dermatemydidae is represented 

in the present collection by several species each 

of the two genera Adocus and Hoplochelys. 

The name Alamosemys, formerly applied to a 

member of this family, is here made a synonym 

of Adocus. This study of most excellent materials, which fully sets forth the detailed 

skeletal structure of these genera, shows the 

necessity of a slight modification in the definition of the family as previously given by Hay.' 

That part of the definition which reads "Neural 

bones reduced in number except in Baptemys" 

should now also include Hoplochelys, here shown 

to possess a full complement of these bones. 

Genus ADOCUS Cope, 1868. 

The genus Adocus, established by Cope 2 in 

1868, was based on Leidy's type of Emys 

beatus, a very fragmentary specimen from the 

Cretaceous greensand of Monmouth County, 

N. J. Since 1868 seven other species of the 

genus have been described by different authors. 

Six of these eight species were founded on 

specimens from the Cretaceous of New Jersey, 

and two (A. lineolatus Cope and A. vigoratus 

Hay) on very fragmentary specimens from the 

Rocky Mountain region—A. lineolatus, from 

the Arapahoe formation of northeastern Colorado, and A. vigoratus, from the Ojo Alamo 

formation of northern New Mexico. An adequate comparison of the species found in the 

East with these two western forms could never 

be made. In the present collection there are 

six fairly complete shells and a considerable 

number of fragmentary specimens which have 

come from the Fruitland, Kirtland, Puerco, and 

Torrejon formations. The discovery of representatives of this genus in basal Eocene deposits gives the first record of its occurrence in 

rocks younger than Upper Cretaceous. 

Five new species are here described, thus 

making the western species more numerous 

than those from the East. The discovery and 

I Hay, 0. P., The fossil turtles of North America: Carnegie Inst. 

Washington Pub. 75, p. 223, 1908. 

2 Cope, E. D., Acad. Nat. Sci. Philadelphia Proc., p. 235, 1868. 

collection of this well-preserved material forms 

a most important contribution to our knowledge 

of the genus Adocus. The specimens are the 

first that are -sufficiently complete to give an 

adequate idea of the bony structure of the 

western forms and thus make a comparison of 

eastern and western species of this genus 

possible. 

The species come from successive geologic 

formations, and certain modifications in structural development appear to be indicated in the 

later species, notably a reduction in size of the 

marginal scutes. In all the Upper Cretaceous 

forms these scutes extend well above the costoperipheral suture, whereas in the Puerco species, 

Adocus hesperius, the costal scutes are enlarged 

and there is a corresponding diminution in the 

size of the marginals. Unfortunately, the two 

species here described, A. onerosus and A. 

annexus, from the Torrej on formation, are based 

on specimens in which the sulci defining the 

posterior marginals can not be made out. A 

closely related form, however, from the same 

formation (Alamosemys substricta Hay 3) has 

the marginals entirely below the costo-peripheral suture. In all other respects Alamosemys 

substricta is essentially an Adocus, and in the 

absence of other distinguishing characters that 

could be considered of generic value I propose 

to regard Alamosemys as a synonym of Adocus. 

Thus the two species now become 

strictus 

annexa 

the type, a well-preserved plastron, with the 

this is the proper disposition of 

is further indicated by a comparison of 

(Hay) and A. annexus (Hay). That 

Alamosemys 

Adocus subplastra of undoubted specimens of Adocus, for 

it is found that they agree quite as closely in 

their general proportions and in the proportions of their constituent parts as the type of 

mosemys, 

parisons. 

A.

A.

A study of this material also shows the utter 

 annexa, 

 annexus 

with which, in describing the species 

Hay 

does with the genotype of 

4 has made the closest comAlafutility of attempting to identify species of 

Adocus from the character of the ornamentation 

of fragmentary specimens. It is now known 

that specimens having the same sculpture of 

the carapace and plastron show important 

Hay, 0. P., The fossil turtles of North America: Carnegie Inst. 

Washington Pub. 75, pp. 260-263, 1908. 

4 Hay, O. P., Description of eight new species of fossil turtles from 

west of the one hundredth meridian: U. S. Nat. Mus. Proc., vol. 38, 

pp. 318-321, 1910. 
26 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

specific differences when a study is made of Species of the Rocky Mountain region—Continued. 

Torrejon species—Continued. their bony structures. Entoplastron broad behind, pointed in front: The accompanying table shows the geologic Anterior lobe rounded; the length of lobe 47

range of the genus Adocus and the position of per cent of the width at the base. 

the several species. Adocus substrictus. 

Geologic distribution of the species of Adocus. 

Age. 	 Western region. Eastern region. 

Adocus onerosus Gilmore, n. sp. 

Torrejon. Adocus annexus (Hay). 

Adocus substrictus (Hay). Basal Eocene. 

Puerco. Adocus hesperius Gilmore, n. sp. 

Arapahoe. Adocus lineolatus Cope. 

Ojo Alamo. Adocus vigoratus Hay. 

Adocus beatus (Leidy). 

Upper Cretaceous. Adocus punctatus Marsh. 

Adocus bossi Gilmore, n. sp. Adocus lacer Hay. Kirtland. Adocus kirtlandius Gilmore, n. sp. 	 Adocus syntheticus Cope. 

Adocus agilis Cope. 

Adocus pravus Leidy. 

Fruitland. Adocus sp. 

The following key, which is an expansion of 

the one given by Hay,' may assist in distinguishing the species: 

Species of the Rocky Mountain region: 

Kirtland species: 

Posterior lobe truncated behind; the length about 

74 per cent of the width at the base. 

Adocus kir tlandius. 

Posterior lobe rounded behind; the length about 

80 per cent of the width at the base. 

Adocus bossi. 

Arapahoe and Ojo Alamo species: 

Sculpture fine, four or five pits in a line 5 millimeters long Adocus lineolatus. 

Sculpture coarse, three pits in a line 5 millimeters long Adocus vigoratus. 

Puerco species: 

Costal scutes higher than wide; posterior marginals reduced in height but overlapping costal 

bones Adocus hesperius. 

Torrejon species: 


Entoplastron rhombic: 


Anterior lobe rounded with slight median 

notch, the length of lobe 43 per cent of the 

width at the base Adocus annexus. 

Anterior lobe truncated; the length of lobe 

33 per cent of the width at the base. 

Adocus onerosus. 

Species of eastern United States: 

Hinder lobe of plastron narrowed behind: 

Entoplastron wide; nearly equal to length of the 

suture between the hyoplastrals. 

Adocus beatus. 

Entoplastron narrow; width nearly twice in the 

hyoplastral suture Adocus pravus. 

Hinder lobe broad behind; rounded or truncated: 

Gulo-humeral sulcus close to or crossing the entoplastron : 

Hinder lobe truncated behind; the length 

between three-fifths and four-fifths the 

width at the base Adocus punctatus. 

Hinder lobe broadly rounded; its length 

three-fifths the width at the base; gulohumeral sulcus just in contact with the 

entoplastron. Adocus syntheticus. 

Hinder lobe broadly rounded; its length fourfifths the width at base; gulo-humeral sulcus 

well forward on entoplastron.. Adocus lacer. 

Gulo-humeral sulcus falling considerably behind 

the entoplastron Adocus agilis. 

Adocus kirtlandius Gilmore, n. sp. 

Plates V and VI. 

Type: No. 8593, U. S. N. M. Consists of 

the carapace, which lacks the front margin and 

the greater parts of all peripherals anterior to 

the inguinal notches, and the plastron, from 1 Hay, 0. P., The fossil turtles of North America: Carnegie Inst. 

Washington Pub. 75, p. 236, 1908. which a considerable portion of the anterior 
ORDER CHELONIA. 27 

lobe is missing. Collected by J. B. Reeside, 

jr., and F. R. Clark, 1916. 

Type locality: About 31 miles south of west 

of Kimbetoh, near the south side of sec. 4, T. 22 

N., R. 10 W., San Juan County, N. Mex. 

Horizon : Kirtland formation (" 75 feet above 

the base"), Upper Cretaceous. 

In addition to Adocus bossi, described below, 

the Kirtland formation contains a smaller 

species which I here designate A. kirtlandius, 

in reference to the geologic occurrence 

of the type specimen. 

Both the carapace and the plastron 

are ornamented with rows of shallow 

pits. These pits are fairly uniform in size 

and are arranged mostly in rows that run 

obliquely across the neurals, costals, and 

peripheral bones. On the plastron these 

rows appear to have a general longitudinal direction. So far as can be judged 

from descriptions and illustrations, the 

present specimen is indistinguishable 

in sculpturing from the type and other 

specimens which have from time to time 

been referred to Adocus lineolatus Cope, 

a species founded on scanty materials 

thought to have come from beds of 

Arapahoe age. I have shown in a previous paper 1 that " turtles having a 

similar surface ornamentation of the 

shell lived in the Judith River, Ojo Alamo, Belly River, Arapahoe, and Lance 

epochs," to which we may add the 

Kirtland and Fruitland epochs. It is 

now apparent that more than one species is represented by these specimens 

that have a similar surface sculpture 

of the shell, and as ornamentation of 

this kind can no longer be relied on as 

broadly rounded. All the bones of the carapace are relatively thin. The peripherals posterior to the inguinal notches are thin and reduced to an acute free edge. They are also 

flared somewhat upward. 

The nuchal region is missing. There are 

seven neuraM present, and, with the exception 

of the sixth, which is reduced in size, they 

closely resemble those of Adocus punctatus 

Marsh, from the Cretaceous of New Jersey. As 

distinguishing A. lineolatus, I shall FIGURE 7.—Carapace of Adocus kirtlandius Gilmore, n. sp. (No. 8593, U.S.N.M.). 

Type. C i, C8, Costal bones 1 and 8; N1,2,3, 4, 5,6,8, neural bones 1 to 6 and henceforth regard A. lineolatus as an 8; py, pygal; spy 2, suprapygal 2; V .1, V 5, vertebral scutes 1 and 5. One-fourth 

indeterminate species. natural size. 

It is estimated that the carapace of 

the type specimen of Adocus kirtlandius (No. 

8593, U.S. N. M.) had a greatest length at the 

center of about 500 millimeters and a greatest 

width of about 350 millimeters. The shape of 

the shell can not be determined from the materials now available. The posterior end, as 

shown by the type (see Pl. V), is evenly but 

1 Gilmore, C. W., Vertebrate faunas of the Ojo Alamo, Kirtland, and 

Fruitland formations: U. S. Geol. Survey Prof. Paper 98, p. 298, 1916. 

in that species, the seventh neural has disappeared, the second and eighth are suboval in 

form, and all others are hexagonal. 

The reduction in size of the sixth neural and 

the loss of the seventh permit the sixth and 

seventh pairs of costals to meet on the midline. 

In Adocus bossi the eighth neural has disappeared and the eighth pair of costals also meet 

on the median line. 
28 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

Measurements of neurals of Adocus kirtlandius (No. 8598, 

U. S. N. M.), in millimeters. 

No. Length. Width. 

1. 32± 

2. _ _ .. 49 23 

3_ _ .. _ 48 30 

4_ ... . 41 27 

5_ _ . _ . 34 29 

6. .... 25.5 25 

7_ 

8_ _ __ . 30.5 15 

Suprapygal 2 is octagonal and has a greatest 

length of 60 millimeters and a greatest width 

of 90 millimeters. 

Only a small portion of the pygal remains, but 

its upper end has a width of 26 millimeters. It 

is estimated that the height of this bone was 

about 54 millimeters. 

The costals have the usual shape and proportions for this genus, except that the eighth 

pair narrow much more rapidly from the median line outward than in any other known 

species. On the under side of the costals the 

rib heads are greatly reduced. 

The sulci are narrow and very shallowly impressed. The vertebral scutes are large in 

front but diminish rapidly toward the back. 

The sides are strongly bracket shaped. The 

peripheral dimensions of these scutes are given 

in the subjoined table. Their shape is 

well shown in figure 7 (p. 27). 

Measurements of vertebral scutes of Adocus kirtlandius a (No. 8.593, U. S. N. M.), in millimeters. 

No. Length. Width. 

2_.... 89 90 

3_ _ .._ 87 83 

4..._. 71 75 

5_ _ ... 63 59 

The costal and marginal scutes appear 

to have the usual conformation,. The 

anterior marginals are small and the 

lateral and posterior are large; there is a 

corresponding reduction in the area of 

the costals from the first to the last. 

The ninth marginal, the longest of the 

series, measures 124 millimeters in height. 

The supracaudal scutes meet along the 

midline for a distance of about 88 milliFIGURE 8.—Plastron of Adorns kirtlandius Gilmore, n. sp. (No. 8593, U. S. N. meters. The first costal scute has a

M.). Type. ab, Abdominal saute; an, anal saute; ent, entoplastron; epi, greatest measurement fore and aft of 120 epiplastron; fem, femoral saute; g, gular saute; hum, humeral saute; hyo, 


hyoplastron; hypo, hypoplastron; in mar, inframarginal scutes; ing, integular millimeters and a heightof 98 millimeters. 


saute; per, median peripherals; pea, pectoral saute; xiph, xiphiplastron. One-
 The last costal scute measures 55 millifourth natural size. 

The peripherals anterior to the eighth are so 

poorly preserved as to give but little information regarding them. The eighth has a width 

along the free border of 65 millimeters and a 

greatest height of 84 millimeters; the ninth is 

57 millimeters wide on the free border and has 

a greatest height of 87 millimeters; the tenth 

is 52 millimeters wide on the free border and 

has a greatest height of 78 millimeters; the 

eleventh is 45 millimeters wide on the border 

and has a greatest height of 63 millimeters. 

meters fore and aft and only 34 millimeters in height. 

The plastron lacks the forward half of the 

anterior lobe, but it is estimated that the total 

length of the plastron would be about 350 

millimeters. The anterior lobe has a width at 

the base of 182 millimeters. The bridge is 160 

millimeters wide. The posterior lobe is 125 

millimeters long and 166 millimeters wide at the 

base. The posterior end is truncated. The 

free edges of this lobe are subacute, as contrasted with the rounded edges in A. bossi. At 
ORDER CHELONIA. 29 

the center of the bridge the plastron has a 

greatest transverse width of 242 millimeters. 

The plastron is strongly joined to the 

peripherals by close sutures. The upper sides 

of the xiphiplastral bones have elongate curved 

depressions for the pubic bones, as in A. 

punctatus Cope. 

The hyoplastrals meet on the midline for a 

distance of about 72 millimeters; the hypoplastrals for 94 millimeters, the left element 

being longer than the right in this dimension. 

The xiphiplastrals meet for 85 millimeters. 

The median longitudinal sulci pursue a very 

irregular course, passing first to one side and 

then to the other of the median line, as is 

shown in figure 8. There are four inframarginal 

scutes on the bridge, the largest one of which 

extends outward over the median bridge peripheral, whereas in A. punctatus these scutes 

are confined entirely to the plastron. 

The pecto-humeral sulcus apparently does 

not cross the entoplastron, just barely reaching 

its posterior border. The pectorals measure 

42 millimeters along the midline, the abdominals 91 millimeters, the femorals 66 millimeters, 

and the anals 62 millimeters. 

The truncated posterior end of the hinder 

lobe of the plastron in Adocus kirtlandius distinguishes it at once from all the eastern members of this genus except A. punctatus Marsh, 

and in fact from all other western species 

in which this portion of the plastron is 

known. Adocus kirtlandius also resembles 

A. punctatus in having a broad anterior 

lobe and the eighth neural. It differs from 

that species in having the pectoral scutes excluded from the entoplastron, in the greater 

relative width of the bridge, and in having 

the vertebral scutes except the third wider 

than long. From A. vigoratus it is distinguished by the finer ornamentation and the 

relatively thinner posterior peripheral bones. 

The characters that now distinguish Adocus 

kirtlandius may be summed up as follows: 

Specific characters: Posterior lobe with truncated posterior end; eighth neural present, 

seventh absent, sixth reduced; all vertebral 

scutes except third wider than long; eighth pair 

of costals with relatively narrow (fore and aft) 

proximal ends. 

Adocus bossi Gilmore, n. sp. 

Plates VII and VIII. 

Type: No. 8613, U. S. N. M. Consists of a 

carapace and plastron, the former lacking the 

greater part of the costals, all the peripherals 

of the right side, and peripherals 4, 5, 9, and 

10 of the left side. The plastron is nearly complete. Collected by J. B. Reeside, jr., 1916. 

Type locality: About 21 miles south of west 

of Kimbetoh, in sec. 3, T. 22 N., R. 10 W., San 

Juan County, N. Mex. 

Horizon: Kirtland formation ("75 feet above 

the base"), Upper Cretaceous. 

The specimen selected as the type of the 

present species is the largest known member of 

the genus. In a straight line the carapace 

measures 670 millimeters in length, and in front 

of the middle it is about 520 millimeters wide. 

The species is named for Mr. N. H. Boss, 

preparator in the section of vertebrate paleontology, whose patience and skill in preparing 

this specimen and in fitting together the great 

number of broken fragments have made it 

possible to recognize and describe the species. 

Although much of the right side of the carapace 

is missing, enough remains to indicate clearly 

all the essential characters of the shell (fig. 9). 

In form the shell is elongate, being broadly 

rounded in front and probably also behind. 

It appears to be widest in front of the middle 

instead of behind it, as in A. punctatus Marsh, 

although there is a possibility that these 

proportions are due to the incompleteness of 

the individual, especially of the posterior 

peripherals. The shell is high through the 

center but slopes off toward either end, so that 

except for being slightly flattened on the 

middle portions it is convex in all directions 

but more steeply inclined in transverse diameter. The posterior peripherals are largely 

missing. Peripheral 8 has an acute edge with 

an inclination to flare upward, but those in 

front of the axillary notches are thickened and 

rounded on the edges, the upper borders rising 

above the general level of the upper surface 

and thus forming a shallow gutter which 

gradually fades out posterior to the center. 

The ornamentation of the carapace and the 

bones of the plastron consist of shallow pits 

arranged in more or less regular rows, which 
30 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

usually run oblique to the sutural borders of 

the bones. This ornamentation is of the coarse 

style, as in A. vigoratus Hay, there being 

usually three pits in a 5-millimeter line. The 

ridges be.tween the pits are rounded, and the 

cross ridges are rather indistinct. This coarser 

sculpture distinguishes this species from A. 

kirtlandius, found in the same formation, which 

has four or five pits in a 5-millimeter line. 

The nuchal bone is shallowly notched on the 

Measurements of neurals of Adocus bossi (No. 8613, U. S. 

N. M.), in millimeters. 

No. Length. Width. 

1 88 38+ 

2_ 59 29± 

3 65 39 

4 57 37 

5. 51 39 

6 32 36 

The second neural is elliptical; the others are hexagonal. The first has the 

broader end behind, the 

others in front. The sixth 

neural interposes itself only 

part way between the sixth 

pair of costals, so that behind this neural these costals 

join on the midline, as do 

the seventh and eighth pairs. 

The single suprapygal is 

large, but its exact contour 

can not be determined from 

this specimen, though it is 

probably octagonal. Fore 

and aft its greatest length is 

90 millimeters. 

The peripherals, as in the 

other species of the genus, 

are large. 

Measurements of peripherals of Adocus bossi (No. 8613, U. S. N. M.), 

in millimeters. 

Length 

No. Height. of free 

border. 

1 80 75 

2 80 78 

3 96 73 

4 109 80 

5 

6 119 69 FIGURE9.—Carapape of Adocusbossi Gilmore, n. sp. (No. 8613, U. S. N. IC). Type. C1, C8, Costal 7 110 73 

bones 1 and 8; N1, 2, 3, 4, 5, 6, neural bones 1 to 6; nu, nuchal; py, pygal; spy 2, second supra- 8 120 75 

pygal. One-fifth natural size. 

midline of the free border. It is 87 millimeters 

long, 90 millimeters in maximum width, and 

69 millimeters wide on the free border. There ­

are six neurals. Those posterior to the sixth 

have disappeared, and the costals meet on the 

median line. 

The pygal, which lacks its posterior extremity, is estimated to measure about 65 

millimeters in height; at the upper end it is 31 

millimeters wide. 

The sulci on both carapace and plastron are 

narrow and shallowly impressed. 
ORDER CHELONIA. 31 

Measurements of vertebrals of Adocus bossi (No. 8613, U. S. 

N. M.), in millimeters. 

No. Length. Width. 

1 123 136 

2 124 104 

3 117 100 

4 113 80 

5 89 65 

The four anterior marginals are small and 

below the costo-peripheral suture, but the fifth 

rises high above the costo-peripheral suture. 

The fourth marginal has a greatest height at 

right angles to the border of 48 millimeters; 

the fifth is at least three times as high. This 

great height of the marginals decreases correspondingly the area of the costal scutes. The 

eighth is 180 millimeters in height and the 

next two are but little lower. The supracaudal 

scutes meet along the midline for a distance of 

about 110 millimeters. The costal scutes diminish in size from the first to the last, as in 

all the other species of this genus. 

The nuchal scute is we'dge-shaped, with the 

point directed forward and barely reaching the 

free margin. It is 20 millimeters long and its 

posterior end is 7 millimeters wide. 

The posterior pair 'of costals, the widest of 

the series, meet on the midline for a distance 

of 57 millimeters. 

The plastron (see fig. 10) is large. The anterior lobe, as in the other species of the genus, 

is short and broad, with a truncated end, but 

the posterior lobe is elongated, with a sharply 

rounded end. The total length of the plastron 

is '510 millimeters. The anterior lobe is 103 

millimeters long, and 255 millimeters wide at 

the base. 

The large entoplastron is subhexagonal in 

outline and measures 105 millimeters in width 

and 70 millimeters antero-posteriorly. The 

bridge is 235 millimeters wide. The length of 

the posterior lobe is 175 millimeters, and its 

width at the base 220 millimeters. The free 

borders of the posterior lobe are subacute, 

being sharply beveled off from the upper side. 

This beveled surface rises above the level of 

the surface so as to form a decided ridge along 

the posterior half of this lobe, which subsides 

before reaching the midline. On the dorsal 

surface on the midline 28 'millimeters forward 

of the posterior border is a subconical projection that stands well above the surrounding 

surfaces. At either side and somewhat forward are well-defined pubic scars. The posterior end of this lobe turns decidedly upward 

from the horizontal. The truncated end of 

the anterior lobe is 80 millimeters wide. On 

either side the free border is thickened (14 

millimeters) and rounded, but more posteriorly 

it thins (7 millimeters) to a narrow rounded 

border. The plastron articulates with the 

carapace by means of buttresses and sutures. 

FIGURE 10.—Plastron of Adocus bossi Gilmore, n. sp. (No. 8613, 

U. S. N. M.). Type. ab, Abdominal scute; an, anal scute; ent, entoplastron; epi, epiplastron; fern, femoral saute; g, gular scute; hum, 

humeral saute; hyo, hyoplastron; hypo, hypoplastron; ing, intergular 

saute; in mar, inframarginal scute; pec, pectoral saute; xiph, xiphiplastron. One-fifth natural size. 

The epiplastra meet on the midline for a distance of 43 millimeters. The right hyoplastron 

is wider than the left, but they meet for a distance of 109 millimeters on the midline; the 

hypoplastron for 137 millimeters; and the 

xiphiplastron for 124 millimeters. 

The sulci are moderately impressed, and the 

longitudinal sulcus runs a very irregular course, 

crossing first to one side and then to the other 

of the median longitudinal suture. The gulars 

are excluded from meeting on the midline by 

the interposition of the intergulars. The 
32 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

intergulars overlap slightly the forward end 

of the entoplastron. They meet on the midline for 57 millimeters, the humerals for 53 

millimeters, the pectorals for 65 millimeters, 

the abdominals for 140 millimeters, the femorals for 74 millimeters, and the anals for 110 

millimeters. 

The species has inframarginal scutes, but 

their number can not be determined from this 

specimen. 

Adocus bossi closely resembles A. vigoratus 

Hay in the character and coarseness of the 

surface sculpture, but it is to be distinguished 

from that species by its larger size and differences to be found in the proportions of the 

eighth peripheral. 

The eighth peripheral of the type of Adocus 

vigoratus Hay was mistakenly identified as the 

seventh in the original description, and this 

error was unrecognized in my subsequent comparison of this bone with a peripheral identified 1 as belonging to A. lineolatus Cope. 

A comparison of the eighth peripheral of 

length (73 millimeters), the height of the former 

ratus 

is 120 millimeters and that of the latter only 

96 millimeters. Other differences noted are 

A. bossi 

shows that while both are of the same 

with the homologous bone in A. vigothat the free border of A. bossi presents a more 

acute edge; the shoulder on the anterior border 

which receives the inguinal buttress of the 

plastron is relatively thinner, and the sculptured surface extends in from the border on 

the ventral side of the peripheral to half its 

height, whereas in A. vigoratus it is considerably less. 

Typically Adocus bossi is the largest species 

of the genus. From A. kirtlandius, of the 

same geologic horizon, it is distinguished by 

the rounded hinder end of the plastron, the 

greater length of the anal scutes, the absence 

of neural 8, the very wide proximal ends of 

the eighth pair of costals, and the vertebral 

scutes longer than wide. From A. h,esperius 

it is distinguished by the coarser character of 

the sculpturing of the shell and in having the 

costal scutes longer than high, whereas in that 

species they are higher than long. 

From tl-ie Torrejon forms Adocus annexus and 

A. substrictus the present species is at once 

distinguished by the truncated anterior end of 

1 Gilmore, C. W., Vertebrate faunas of the Ojo Alamo, Kirtland, and 

Fruitlani formations: U. S. Geol. Survey Prof. Paper 98, pp. 297-298, 

1916. 

the plastron as contrasted with the rounded 

lobes in A. annexus and A. substrictus. Adocus 

onerosus, found in the same formation, has a 

truncated anterior lobe, but the relative proportions are quite unlike in the two species. 

In A. bossi the length of the anterior lobe is 40 

per cent of the width, whereas in A. onerosus 

it is 33 per cent of the width. The rhomboid 

shape of the entoplastron. of A. onerosus will 

also assist in distinguishing these forms. 

The characters which now appear to distinguish Adocus bossi are as follows: 

Specific characters: Typically of large size; 

anterior lobe truncated, length 40 per cent of 

width at base; posterior lobe rounded; seventh 

and eighth neurals suppressed, sixth reduced; 

all vertebrals except first longer than wide; 

eighth pair of costals meeting wide on midline; anterior border of carapace but slightly 

excavated for the neck, entoplastron broad 

behind, pecto-humeral sulcus falling somewhat behind the entoplastron; sculpture coarse, 

three pits in 5-millimeter line. 

A second specimen (No. 8577, U. S. N. M.) 

from the same locality and the same geologic 

horizon as the type of Adocus bossi is here provisionally identified as pertaining to that 

species. It consists of a complete plastron 

firmly joined by the bridge peripherals to the 

damaged central part of the carapace, as shown 

in Plate VIII. The carapace lacks much of 

the forward , end as well as suprapygal 2 and 

the peripherals of the posterior end. The 

specimen is a considerably smaller individual 

than the type, and while in the main features 

these specimens closely agree, there are other 

minor differences, as will be shown later. 

The carapace of this specimen, though 

badly damaged by crushing and the loss of 

important parts, shows that there were six 

neurals in the same state of reduction as in 

the type. The sixth neural being much 

reduced in size and the seventh and eighth 

entirely gone, the corresponding costals of 

opposite sides meet on the midline. As in the 

type, the eighth pair are especially wide at 

the center. 

The plastron is in a beautiful state of preservation and clearly shows all the sutures between the different bones and all the sulci 

defining the dermal scutes. The greatest 

length of the plastron at the center is 380 

millimeters. As in the type of A. bossi, the 
ORDER CHELONIA. 33 

anterior lobe is short and broad and has a 

truncated anterior end. The anterior lobe is 

88 millimeters long and 205 millimeters wide 

at the base. The entoplastron is broad behind, pointed in front, and overlapped by the 

intergular scutes; the pectoral-humeral sulcus 

barely reaches its posterior border. 

The posterior lobe is relatively shorter than 

in the type, the posterior end is more broadly 

rounded, and the areas of the anal scutes are 

somewhat reduced. None of these differences, 

however, could be considered as representing 

more than individual peculiarities. 

This specimen shows that Adocus bossi has 

three inframarginal scutes. The middle one 

is 93 millimeters long and 21 millimeters wide, 

and in the proportions of this scute A. bossi 

closely resembles A. lacer Hay, from the New 

Jersey Cretaceous. The bridge region in the 

type of A. bossi is so damaged that it is impossible to determine either the number or the 

shape of these scutes. 

The principal dimensions of the bones forming the plastron along the center line in specimen No. 8577 are as follows: The epiplastrals 

meet for 29 millimeters; the hyoplastrals differ 

in this measurement, the left being 77 millimeters and the right 92 millimeters fore and 

aft; the hypoplastrals likewise differ on the 

two sides, the left measuring 105 millimeters 

and the right 96 millimeters; the xiphiplastrals 

meet for 99 millimeters. 

The intergulars meet on the median line for 

25 millimeters, the pectorals for 44 millimeters, 

the humerals for 47 millimeters, the abdominals for 102 millimeters, the femorals for 68 

millimeters, and the anals for 71 millimeters. 

The area of the anals is considerably less than 

in the type specimen. 

Adocus hesperius Gilmore, n. sp. 

Plate IX. 

Type: No. 8596, U. S. N. M. Consists of 

the carapace, lacking the anterior border and 

the peripherals and distal parts of the costals 

of the left side. (See fig. 11.) Collected by 

J. B. Reeside, jr., 1916. 

Type locality: Four miles northwest of 

Kimbetoh, in secs. 27 and 22, T. 23 N., R. 9 W., 

San Juan County, N. Mex. 

Horizon: Puerco formation ("50 feet above 

the base"), basal Eocene. 

115836°-19 3 

The specimen selected as the type of the new 

species Adocus hesperius has additional interest 

in being the first representative of the genus to 

be found in the Puerco formation. 

In the type specimen the carapace is crushed 

flat, which makes it impossible to determine 

anything of the transverse contours of the 

shell. By a comparison with other specimens 

it is estimated that the carapace when complete had a total length at the center of about 

480 millimeters. The greatest width at the 

center, as now flattened out, is 440 millimeters; 

in life it probably measured somewhat less. 

Viewed from above the posterior end of the 

shell is regularly rounded. Behind the inguinal notch the free borders of the peripherals 

present acute edges, and, as in A. kirtlandius, 

these bones have a tendency to flare upward. 

The first neural and the anterior half of the 

second neural are missing. The series in this 

species, as in A. bossi, consists of six neurals, 

and the sixth one is reduced in size. The 

dimensions of those preserved are given in the 

table: 

Measurements of neurals of Adocus hesperius (No. 8596, 

U. S. N. M.), in millimeters. 

No. Length. Width. 

3. .... 45 27 

4_ _ ... 37 23 

5 . .... 34 24 

6_ _ _ _ 28 21 

On account of the suppression of the seventh 

and eighth neurals and the reduction in size of 

the sixth neural, the sixth, seventh, and eighth 

pairs of costals meet on the median line. The 

eighth pair measure 38 millimeters fore and 

aft where they join at the middle but taper 

down to a width of only 13 millimeters at their 

outer extremities. 

There is a single large pentagonal second 

suprapygal. It is 73 millimeters in length 

along the midline and has a greatest width of 

111 millimeters. 

The pygal bone is 57 millimeters high and 

56 millimeters in transverse diameter. 

The eleventh peripheral bone is 58 millimeters wide on the free border and 64 millimeters high, the tenth 53 millimeters wide and 

79 millimeters high, the ninth 54 millimeters 

wide and 81 millimeters high, the eighth 56 
34 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

millimeters wide and 81 millimeters high, the 

seventh 60 millimeters wide and 77 millimeters 

high, and the sixth 58 millimeters wide and 79 

millimeters high. 

outward beyond the costo-peripheral suture. 

The second costal has a length of 85 millimeters and a height of 96 millimeters; the 

third is 81 millimeters long and 91 millimeters 

in height; the fourth is 56 millimeters 

long and 62 millimeters in height. 

The marginal scutes of A. hesperius 

are reduced in height as compared 

with those of the Cretaceous species 

of Adocus. 

The type specimen shows that all 

marginals posterior to the fifth extend 

above the costo-peripheral suture. On 

the assumption that the complete 

series consists of eleven marginals, 

the dimensions of those posterior to 

the fifth are given in the table below. 

Measurements of the marginals of Adocus 

hesperius (No. 8596, U. S. N. M.), in 

millimeters. 

Width 

No. Height. on free 

border. 

6.... 93± 60 

7.... 94± 60 

8.. _ _ 85 59 

9.... 104 62 

10.... 104 56 

11.. _ . 104 51 

The whole surface of the carapace 

is ornamented with small shallow 

FIGURE 11.—Carapace of Adocus hesperius Gilmore, n. sp. (No. 8596, U. S. N. M.). pits. On the peripherals these pits Type. C 3, C 8, Costal bones 3 and 8; N 2, 3, 4, 5, 6, neural bones 2 to 6; py, pygal; 


spy 2, second suprapygal; V 2, V 5, vertebral scutes 2 and 5. One-fourth natural are arranged in rows that assume 


size. 

The vertebral scutes are relatively large, 

especially the fifth. 

Measurements of vertebrals of Adocus hesperius (No. 8596, 

U. S. N. M.), in millimeters. 

No. Length. Width. 

2 80 

3 85 75 

4 77 67 

5 87 83 

The supracaudal scutes meet along the 

midline for a distance of 83 millimeters. 

The costal scutes are higher than long, 

whereas in all other species the length exceeds 

the width. In this respect this species shows 

a development in the direction of A. substrictus, 

of the Torrejon, in which the costals extend 

an oblique direction to the longer axes 

of the bones. On the surface of the costals, 

and especially within the area of the vertebral scutes, the pits are not so well defined, 

being hardly more than longitudinal valleys 

between rounded ridges that are narrower than 

the depressions; the cross ridges are commonly 

absent or, if present, are low and barely 

discernible. 

The finer sculpture of A. hesperius, which 

has four pits in a line 5 millimeters long, distinguishes this species at once from both A. 

vigoratus Hay and A. bossi, which have only 

three pits in a 5-millimeter line. 

The absence of the plastron in the type of 

Adocus hesperius makes it difficult to contrast 

this species with the eastern members of the 

genus. It is distinguished, however, from all 

known species in which the carapace is pre-
ORDER CHELONIA. 35 

served, except the Torrejon forms, by the proportions of the costal scutes, which are higher 

than long. The finer sculpture and more 

rounded form of the pits forming the surface 

ornamentation will separate the present species 

from A. vigoratus Hay, from the Ojo Alamo 

formation. The posterior marginal scutes, 

extending slightly above the costo-peripheral 

suture, distinguish 

strictus, 

exclusively to the peripheral bones. From 

in which these marginals are confined 

A. hesperius from A. subA. 

onerosus and A. annexus the present species 

is to be separated by the better-defined 

osus 

pattern of the sculpture, and from 

than wide instead of wider than long. 

ters appears to be diagnosticof this species: 

The following combination of characby having the vertebral scutes longer 

A. onerSpecific characters: Seventh and eighth 

neurals suppressed, sixth reduced; vertebral scutes longer than wide; fifth vertebral unusually large; eighth pair of costals meeting wide on the midline; costal 

scutes higher than long; posterior marginals reduced in height; sculpture made 

up of rounded pits; three pits in 5-millimeter line. 

Adocus onerosus Gilmore, n. sp. 

Plate X, figures 1 and 2. 

Type: No. 8594, U. S. N. M. Consists 

of a considerable part of a poorly preserved carapace, which lacks most of the 

peripherals, except those of the median 

anterior border, and the plastron, which 

lacks the posterior ends of the xiphiplastral 

bones. 

The few posterior peripherals present in 

specimen No. 8594 show no marginal sulci 

crossing them at right angles, and their absence 

leads to the conclusion that the scutes extended 

above the costo-peripheral suture overlapping 

the costal bones, as in all known specimens of 

Adocus. This genus has not before been recognized in the Torrejon formation, and the 

discovery of the type of A. onerosus and another 

specimen, described below, thus materially 

extends its previously known geologic range. 

FIGURE 12—Carapace of Adocus onerosus Gilmore, n. sp. (No. &594, U.

Type locality: Eight miles N. 60° E. of N. M.). Type. C i, First costal bone; Ni, 2,3, 4, 5,6, neural bones 1 to, 

6; nu, nuchal; per 1, peripheral 1; VI, V4, vertebral scutes 1 and 4. One, Kimbetoh, in sec. 17, T. 23 N., R. 8 W., fifth natural size. 

San Juan County, N. Mex. 

Horizon : Torrej on formation (" 840 feet above 

the base of Puerco, in Torrej on") , basal Eocene. 

The specimen here designated as the type 

of the new species Adocus onerosus is, like 

many other fossil specimens from the Torrejon formation, in so poor a state of preservation as to leave many points in the structure 

of its anatomy undetermined. Not only has 

the carapace suffered much from crushing and 

the loss of important parts, but the coalescence 

of many of the sutures and the obscureness of 

the sulci render the study of the individual 

bones and dermal scutes difficult. 

The type specimen is a large individual, the 

carapace of which is estimated to have had in 

life a total length at the center of about 600 

millimeters. The contours of the front border, 

both horizontal and vertical, have been preserved, though elsewhere the carapace is 

crushed out flat. It shows this end to have 

been broadly rounded, with a pronounced 

emargination for the neck at the middle. (See 

fig. 12.) 

The nuchal, one of the few bones in this 

specimen to be clearly differentiated, is hexagonal. It has a greatest length of 76 milli-
36 REPTILIAN PATINAS OF SAN JUAN COUNTY, N. MEX. 

meters and a greatest width of 102 millimeters, 

and its free border is only 43 millimeters wide. 

Near the anterior rim and on the bordering 

peripherals the nuchal flares upward. 

FIGURE 13.—Plastron of Adocus onerosus Gilmore, n. sp. (No. 8594, 

U. S. N. M.). Type. ent, Entoplastron; epi, epiplastron; g, gular 

scute; hyo, hyoplastron; hypo, hypoplastron; ing, intergular scute; 

xiph, xiphiplastron. One-fifth natural size. 

The exact number of neurals forming the 

series in this species can not be determined from 

the type specimen, but that it is not more 

than six is clearly shown by the sutural union 

on the median line of the seventh and eighth 

pairs of costals. The anterior neurals appear 

to have the shape and proportions indicated in 

figure 12, but some uncertainty still exists as 

to their exact limits. As identified here the 

first neural is 62 millimeters long, the second 

54 millimeters long, the third 48 millimeters 

long and 35 millimeters wide, the fourth 43 

millimeters long and 33 millimeters wide, the 

fifth 36 millimeters long. The existence of a 

sixth neural can not certainly be determined. 

As in A. bossi, the eighth pair of costals meet 

for a considerable distance (48 millimeters) on 

the median line. 

Of the bones forming the borders of the shell 

only peripherals 1, 2, and 3 of the anterior end 

and a few badly preserved ones posterior to the 

inguinal notches are preserved. The first 

peripheral has a width on the free border of 67 

millimeters and a height of 65 millimeters; the 

second is 56 millimeters wide and 64 millimeters high; the third is 52 millimeters wide. 

The costal sutures are nearly all plainly discernible, as shown in figure 12. 

The nuchal scute is small and V-shaped with 

the point forward. It is 24 millimeters long 

and 9 millimeters wide at the posterior end. 

The first marginal has a width of 58 millimeters 

and a height of 36 millimeters; the second is 57 

millimeters wide and 46 millimeters high; the 

third is 54 millimeters wide. 

The vertebrals are exceptionally short and 

wide. 

Measurements of vertebrals in Adocus onerosus (No. 8594, 

U. S. N. M.), in millimeters. 

No. Length. Width. 

1. 90 180 

2 101 116 

3 -85 119 

4 102 103± 

The posterior peripherals are all badly preserved. Their free edges are acute and they 

show the same tendency to flare upward as in 

other species. 

The whole surface of the carapace is ornamented with pittings that on the peripherals 

appear to be arranged diagonally to the longer 

axis of the bones. Toward the center of the 

shell there appears to be no pattern or at least 

nothing more than rather obscure longitudinal 

groovings. 

The plastron is complete except for the 

greater portion of the bridges and the posterior 

end of the xiphiplastrals. 

The anterior lobe is broadly truncated, and 

the truncated end is broadly and angularly 

concave. The length of the anterior lobe is 72 

millimeters and its greatest width at the base 

is 215 millimeters. The anterior border presents a blunt edge which at the center is only 

5 millimeters in thickness. 

The entoplastron is subrhombic, 65 millimeters long and 87 millimeters wide. The 

length of the posterior lobe can not be determined; its width at the base is 183 millimeters. The free edge is acute up to the 

inguinal buttress. Near the edge this part of 

the plastron is only 5 millimeters thick, but 20 

millimeters toward the center from the edge 

the bones increase to 13 millimeters in thickness. The posterior lobe near the position of 

the femoral sulcus shows a marked contraction, and the whole border of the lobe appears 

to have rounded in rapidly toward the center, 

as restored in figure 13. 

The epiplastrals meet on the median line for a 

distance of 23 millimeters, the hyoplastrals for 

70 millimeters, and the hypoplastrals for 107 

millimeters. It is estimated that the bridge 
ORDER CHELONIA. 37 

had a width of 148 millimeters. Of the sulci 

only those bounding the gular and intergular 

scutes can now be recognized. The intergulars lap over the forward end of the entoplastron. They meet on the midline for a 

distance of 35 millimeters, and their combined 

width is 64 millimeters. 

The whole surface of the plastron appears to 

have been covered with some obscure pitting, 

the exact character of which can not be made 

out in this specimen. 

Additional and corroborative information 

relating to the plastron of this species is furnished by two other specimens. 

Specimen No. 8650, U. S. N. M., is from the 

same locality and geologic horizon as the type 

and consists of the articulated epiplastra and 

a portion of the entoplastron. It shows the 

same truncated end with abrupt border. This 

specimen is the only member of the species 

known at this time which shows an accurate 

outline of the anterior half of the entoplastron. 

The two sides meet at the center, forming an 

obtuse angle of about 135°. 

Specimen No. 8649, U. S. N. M., consists of 

the greater portion of a plastron, of about the 

same proportions as the type specimen. Unfortunately the precise locality and geologic 

horizon where this specimen was obtained 

are unknown, though in all probability about 

the same as those of the type. Its chief importance at this time is in being the first 

specimen to show the extent of the plastral 

scutes posterior to the intergulars. The intergulars overlap the forward end of the entoplastron, which is missing in this specimen. 

The pectorals reach the posterior border of 

the entoplastron but do not overlap; they 

measure 40 millimeters along the median line. 

The pecto-humeral sulcus curves forward 

very little at the center; the pecto-abdominal 

sulcus swings backward with a considerable 

sweep. In all other species this condition is 

reversed. The abdominals meet on the midline for 87 millimeters, the femorals for 69 

millimeters. 

Adocus onerosus resembles A. bossi in having 

a truncated anterior lobe, but the length of 

this lobe is only 33 per cent of the width at 

the base, a proportion that is considerably less 

than in any other known species of the genus. 

It resembles A. annexus (Hay) in the rhombic form of the entoplastron, in the obscure 

character of the ornamentation, and in the 

well-defined median excavation of the anterior 

boarder of the carapace for the reception of 

the neck. It can be distinguished from that 

species, however, by difference found in the 

shape and proportions of the anterior lobe, so 

plainly seen by a comparison of figures 13 

and 14. 

The specific characters of Adocus onerosus 

may be enumerated as follows: 

Specific characters: Anterior lobe of plastron 

truncated; length 33 per cent of width at base; 

epiplastrals meeting for a relatively short distance on midline; entoplastron rhombic; overlapped in front by intergulars; anterior border 

of carapace with pronounced median excavation for reception of neck. Sculpture having 

obscure pattern. 

Adocus annexus (Hay) Gilmore. 

Plate XI, figures 1 and 2; Plate XII. 

Alamosemys annexa Hay, U. S. Nat. Mus. Proc., vol. 38, 

pp. 318-321, fig. 19, 1911. 

This species was established by Hay on a 

well-preserved plastron (No. 6539, U. S. 

N. M.) found by J. H. Gardner, of the United 

States Geological Survey, in sec. 1, T. 34 N., 

R. 8 W., in the Ignacio quadrangle, La Plata 

County, Colo. 

A comparison of this plastron with that of 

the genotype of Alamosemys (A. substricta 

Hay) showed such close similarities as to bring 

about its reference to that genus. 

Alamosemys was distinguished from Adocus 

by a single character, the restriction of the 

marginal scutes to the peripheral bones. In all 

found in the Puerco formation, shows an enlargement of the costal scutes and a correpresent collection the species 

other respects the specimens referred to 

semys are essentially like 

Adocus hesperius, 

Adocus. In the 

Alamosponding reduction in the height of the marginals, which still, however, rise above the 

costo-peripheral suture. It would appear, 

therefore, that Adocus substrictus (Hay), of the 

Torrejon formation, might well represent the 

next stage in the progressive reduction of the 

marginal scutes. In the absence of other distinguishing characters which might be con- , 

sidered of generic value, I now regard 

semys 

two species become 

as a synonym of 

Adocus substrictus 

Adocus, and thus the 

Alamo­

(Hay) 

and A. annexus (Hay). 
38 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

The soundness of the above conclusion appears to be further strengthened by a study 

of two specimens from the Torrejon formation 

in the present collection, which in their main 

features clearly belong to the genus Adocus. 

Unfortunately the sulci defining the posterior 

marginals can not be traced in these specimens, 

so that the extent of the marginal scutes can 

not be determined. One is described in the 

present paper as the type of the new species 

A. onerosus, the other (No. 8606, U. S. N. M.) 

plastron of specimen No. 8606 confines the contrasting of the specimens to the general proportions of the plastra and of the individual 

bones which make up that part of the shell. 

In the accompanying table are presented 

various comparative measurements of the 

plastra of the type specimens on which Adocus 

annexus (Hay) and Adocus substrictus (Hay) 

were founded and specimen No. 8606. The 

first three columns give actual measurements; 

the fourth column contains the measurements 

FIGURE 14.—Plastron of Adocus annexus (Hay) (No. 6539, 

U. S. N. M.). Type. ab, Abdominal scute; an, anal scute; 


eat, entoplastron; epi, epiplastron; g, gular scute; hum, 


humeral scute; hyo, hyoplastron; pec, pectoral scute; fem, 


' femoral scute; hypo, hypoplastron; ing, intergular; in mar, FIGURE 15.—Plastron of Adocus annexus (Hay) (No. 8606, U. S. N. M.); eat, 

inframarginals; xiph, xiphiplastron. One-fourth natural Entoplastron; epi, epiplastron; hyo, hyoplastron; hypo, hypoplastron; xiph, 

size. xiphiplastron. One-fourth natural size. 

is here provisionally referred to A. annexus. 

This specimen consists of the damaged carapace (see Pl. XII) and the complete plastron. 

It was collected by J. B. Reeside, jr., 8 miles 

N. 60° E. of Kimbetoh, in sec. 17, T. 23 N., 

R. 8 W., San Juan County, N. Mex., in the 

Torrejon formation (" 840 feet above base of 

Puerco, in Torrejon") basal Eocene. 

The specific identity of this specimen with 

the type of Adocus annexus (Hay) appears to be 

established by a comparison of the plastra 

of the two specimens. (See figs. 14 and 15.) 

The obliteration of nearly all the sulci on the 

of the first column reduced 16 per cent, and the 

fifth column contains the measurements of the 

second column reduced 15 per cent, the length 

of the anterior lobe of the type of A. annexus, 

84 millimeters, being made the standard. A 

comparison of the measurements in the third 

column with those in the fourth and fifth 

columns shows at once the differences between 

No. 8606 *and A. substrictus, and the close 

resemblance of No. 8606 to A. annexus. 

The rhombic shape of the entoplastron in 

specimen No. 8606 is further evidence of its 

specific identity with A. annexus. 
ORDER CHELONIA. 39 

Comparative measurements of plastra of Adocus, in millimeters. 

Reduced measure- True measurements. ments. 

A. annexus. 

A. sub- A. sub- A. anstrictus strictus nexus 

(type). No. 8606. No. 6539 

(type). 

(type). (No. 8606). 

Length of anterior lobe 100 99 84 84 84 

Width of anterior lobe 209 230 177 175 195 

Thickness of edge near front 9 8 8 7. 5 7. 8 

Length of entoplastron 55 65 51 46 55 

Width of entoplastron 90 87 71 76 74 

Width of bridge 180 185 160 151 157 

Length of posterior lobe 132 120 100 110 102 

Width of posterior lobe 190 182 163 160 155 

Contact of hyoplastral bones 100 78 72± 84 66 

Contact of hypoplastral bones 135 107 100± 113 91 

Contact of hyoplastral and hypoplastral 

bones taken together 235 185 173 197 158 

Length of intergular sulcus 50 43 42 

Combined width of intergulars 75 78 65 63 66 

The detailed description of the plastron of 

A. annexus as given by Hay is as follows: 

The anterior lobe is rounded in front, without appearance of epiplastral lip. Its free borders are subacute. 

Seen from above, the bones thicken from this edge, until 

at about 15 millimeters from the edge they have a thickness 

of from 7 to 9 millimeters. The upper surface of the lobe 

is nearly flat. The buttresses, anterior and posterior, are 

little developed. The entoplastron differs from that of 

A. substricta in being somewhat pointed behind, instead 

of rounded or subtruncated. It is longer than that of 

A. substricta in the ratio of 51 to 46 and narrower in the 

ratio of 71 to 76. It will be observed that there is a union 

of the left hyoplastron with the right hypoplastron and a 

similar connection between the latter bone and the left 

xiphiplastron. Such irregularities are probably only individual peculiarities, but similar ones are quite common 

among the ancient turtles. 

It is seen that the hyoplastra and the hypoplastra are 

shorter than in A. substricta, relatively to the length of 

the anterior lobe. The bridge, too, is shorter. The free 

border of hinder lobe is somewhat less acute than that of 

the anterior lobe. At the hypo-xiphiplastral suture the 

bones are 9 millimeters thick. On the midline, 30 millimeters behind the suture just mentioned, the thickness is 

only 7 millimeters. The free borders of the xiphiplastrals 

posteriorly are acute. On the upper surface of each 

xiphiplastral there is a crescentric elevation for attachment of the pubic bone. 

The lower surface of the plastron is very indistinctly 

sculptured. The appearance is as if there were rows of 

small pits as in Adocus, but they are so faintly impressed 

that they are hardly to be detected. 

It will be seen that many of the horny scutes had very 

irregular boundaries. Especially the median sulcus runs 

a very tortuous course. The gular and intergular scutes 

differ little from those of A. substricta. The humeropectoral sulcus crosses the hinder border of the entoplastron. In A. substricta the sulcus is only tangent to the 

bone. The line of contact between the right and the left 

humerals is thus shorter than in A. substricta in the ratio 

of 28 to 40. * * * The pectorals of the two species 

have the same relative length as also the abdominals have. 

The hinder lobe of A. annexa is more narrowed posteriorly 

than that of A. substricta. On each bridge there are four 

inframarginal scutes, which resemble closely those of the 

type of the genus. 

The plastron of specimen No. 8606 at the 

center measures 395 millimeters in length. 

The anterior lobe is 99 millimeters long and 

230 millimeters wide at the base. The length 

of this lobe is therefore 43 per cent of the 

width, whereas in Adocus onerosus it is only 

33 per cent. The anterior lobe is rounded, as 

in the type of A. annexus, but the hinder lobe 

has a relatively broader posterior extremity, 

which resembles that of A. substrictus more 

nearly than it does that of the type of A. 

annexus. 

Only the gular-intergular sulcus can be 

made out, and it shows that the forward end 

of the entoplastron was overlapped somewhat 

by the intergular scutes. 

The surfaces of both carapace and plastron 

are ornamented with pittings, but this specimen is so poorly preserved that the pattern is 

obscure. A considerable portion of the anterior and median part of the carapace is preserved with this specimen, and although only 

a few of the sutures and none of the sulci can 

be traced, it is important as giving us the first 

information regarding the upper shell of this 
40 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

species. It shows the anterior end of the 

carapace to have been broadly rounded, with 

a pronounced median excavation for the neck 

of the animal. In the contour of this end of 

the carapace it shows a striking resemblance 

to Adocus onerosus, described above, and also 

to A. substrictus. 

The nuchal plate is 89 millimeters long and 

has a greatest width of 94 millimeters and a 

width on the free border of 58 millimeters. 

The upper surface of this bone as it approaches 

the free border flares upward, like the bordering peripherals. 

The first peripheral is 62 millimeters wide 

and 63 millimeters high; the second 55 millimeters wide. None of the other bones have 

been differentiated. 

Adocus annexus may now be characterized 

as follows: 

Specific characters: Anterior lobe rounded, 

with slight median notch; length 43 per cent 

of width at base; posterior lobe rounded; 

seventh and eighth neurals suppressed; vertebrals wider than long; eighth pair of costals 

meeting for a considerable distance on midline; entoplastron rhombic overlapped by both 

intergular and pectoral scutes. 

Genus HOPLOCHELYS Hay, 1905. 

The study of the excellent collection of 

Hoplochelys material now enables me to define 

the genus as follows: 

A genus of the Dermatemydidae. External surfaces of the shell finely shagreened. 

Carapace flattened on top and having three 

dorsal carina. Eight neurals. Eleven peripherals, which unite with the plastral bones 

by means of digitations and dentated sutures; 

with the costals by gomphosis, and in young 

by simple apposition with pits for distal prolongations of costals, in adults by close sutures. 

Plastron cruciform, with anterior and posterior 

lobes immovable, and with the posterior narrow end pointed. A row of inframarginal 

scutes on each bridge. Pectoral and femoral 

scutes meeting and crowding the abdominals 

from mutual contact at the midline. Intergulars and gulars wanting or consolidated 

with the humerals. 

All the known specimens of this genus, with 

the exception of the type of Hoplochelys 

coelata Hay, from the Fort Union of Montana, 

have come from the basal Eocene deposits of 

New Mexico. Seven species are now recognized, two of which are described as new in 

the present paper. 

The type of the genus is Hoplochelys crassa 

(Cope), a fragmentary specimen, which is now 

thought to be an immature individual, so that 

some of the characters formerly used for distinguishing the species can no longer be regarded as valid specific differences. Fortunately an articulated specimen (No. 8525, 

U. S. N. M.), consisting of the greater part of 

the carapace and the median portion of the 

plastron, appears to be referable to this species 

and for the first time gives a comprehensive 

idea of the chief characteristics of the species. 

With the exception of H. paludosa Hay, 

based on a single peripheral, the other Torrejon 

species of the genus Hoplochelys may at once 

be distinguished from the Puerco representatives by their relatively wider vertebrals and 

neurals. 

Of the seven described species five have 

been recognized in the present collection, all 

represented by well-preserved specimens. 

These show that there was a full complement 

of eight neural bones, a feature in which this 

genus differs from all other members of the 

family Dermatemydidae, except Baptemys, 

thereby requiring a slight modification in the 

definition of that family. 

The accompanying table shows the geologic 

distribution of the species. 

Hay 1 regards Hoplochelys as being doubtfully related to Staurotypus, now living in 

southern Mexico and Guatemala, of which 

Sumichrast 2 says: 

It lives in muddy pools. Its food consists of small 

aquatic animals, especially of mollusks belonging to the 

genus Ampullaria. Its disposition is voracious and irritable. Its gait on land is free, and it runs with some 

swiftness, a fact due to the form of the plastron, which 

leaves to the limbs freedom of motion. 

Hay 3 observes: "The small posterior lobe 

of the plastron of Hoplochelys indicates that 

the hinder limbs were strong and endowed 

with freedom of movement. Its habits and 

disposition may have been not greatly different 

from those of Staurotypus." 

1 Hay, 0. P., The fossil turtles of North America: Carnegie Inst. 

Washington Pub. 75, p. 263, 1908. 

2 Soc. tool. France Bull., 1880, p. 169. 

Op. cit., p. 266. 
ORDER CHELONIA. 41 

Geologic distribution of the species of the genus Hoplochelys. 

Fort Union. Hoplochelys coelata Hay. 

Hoplochelys saliens Hay. 

O 

Torrejon. Hoplochelys elongata Gilmore, 

Hoplochelys paludosa Hay. 

4.1 n. sp. 

2 

Puerco. 

Hoplochelys crassa (Cope). 

Hoplochelys bicarinata Hay. 

Hoplochelys laqueata Gilmore, 

n. sp. 

Hoplochelys crassa (Cope) Hay. 

Plate XIII. 

Dermatemys sp. Cope, Am. Philos. Soc. Proc., vol. 20, p. 

461 (no description), 1882. 

Chelydra crassa Cope, Science, vol. 11, p. 198 (no description), 1888; Am. Philos. Soc. Trans., 2d ser., vol. 

16, p. 306, 1888. 

Hay, Bibliography and catalogue of the fossil Vertebrata of North America: U. S. Geol. Survey Bull. 

179, p. 446, 1902. 

Hoplochelys crassa (Cope) Hay, Am. Geologist, vol. 35, p. 

339, 1905; The fossil turtles of North America: Carnegie Inst. Washington Pub. 75, pp. 263-265, text 

fig. 325, pl. 38, figs. 4-9, 1908. 

Matthew, W. D., Geol. Soc. America Bull., vol. 25, 

p. 383, 1914. 

Hoploch,elys crassa was established by Cope 

on the remains of two individuals. Hay,' in 

discussing this species, says of these : 

Of the first there were present two vertebral bones, nine 

peripherals, and three plastrals; of the second, three vertebrals. The bones of the first-mentioned individual are 

now in the American Museum of Natural History and bear 

specimen No. 6091 was lent to me for study 

ond 

the catalogue number 6091; where the remains of the 

Through the kindness of Dr. W. D. Matthew, 

specimen are is not at present known. 

sec­ with the present collection, and by comparison 

with it I have identified three individuals as 

pertaining to this species. These bear the 

catalogue Nos. 8525, 8641, and 8643, U. S. N. M. 

No. 8525 has a considerable part of the carapace 

preserved and is the first specimen to give 

adequate information as to the shape and general proportions of the shell. (See Pl. XIII.) 

The principal characters for distinguishing 

the species Hoplochelys crassa, as pointed out 

by Hay, are in "having the bones of the plastron less firmly sutured with the latter bones, 

at least those of the bridge region, without close 

1 _The fossil turtles of North America: Carnegie Inst. Washington 

Pub. 75, p. 236, 1908. 

suture with the costals." This is precisely the 

condition noted in both Nos. 8641 and 8643, a 

condition which I will attempt to demonstrate 

is due to the immaturity of the individuals. 

In the type of H. crassa (Cope), now before me, 

the few peripherals present have the upper borders smooth—that is, without sutural edges— 

and the upward extension of these bones above 

the costo-marginal sulcus is exceedingly short. 

In all other respects, including the deep pits on 

the inner side for the costal rib extensions, these 

bones are identical with those which have a 

higher development of the bone above the 

costo-marginal sulcus and which are suturally 

united with the ends of the costals. It is also 

significant that all three of the specimens showing this peculiarity of the peripherals are much 

smaller individuals than any of those in which 

the sutural union of the peripherals and costals 

has been perfected. Additional evidence of the 

immaturity of specimen No. 8643 is furnished 

by the unfinished character of the sutural surface on the hyoplastron. for union with the 

epiplastron, which in all larger individuals is 

strongly and clearly defined. 

It would thus appear that the species H. 

crassa (Cope) was founded on a juvenile specimen and that the characters heretofore used 

for distinguishing the species are largely due 

to the immaturity of the individuals and can 

not be relied upon as being constant specific 

differences. However, specimen No. 8525, 

which agrees in all other respects with the 

type of H. crassa, such as having sharp lateral ­

keels and well-defined carinae crossing the 

bridge peripherals, now shows other characters 

that clearly distinguish the species, and on that 

account I now give a detailed description of 

this specimen. 

Specimen No. 8525, U. S. N. M., consists of 

the greater part of the carapace and median 

portion of the plastron. (See fig. 16.) Several of the neurals and portions of the costals 

and peripherals are missing. The specimen 

was collected by J. B. Reeside, jr., in 1916, 4 

miles east of Kimbetoh, in sec. 35, T. 33 N., 

R. 9 W., San Juan County, N. Mex., 50 feet 

above the base of the Puerco formation. 

Although lacking many important parts, this 

specimen is nevertheless perfect enough to 

give a very good idea of the shape and propor­

.tions of the shell of this species. 
42 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

The carapace is moderately elongate oval, 

slightly truncated in front by the very narrow 

excavation for the neck, and pointed behind, 

as in H. laqueata. The posterior end of the 

carapace has a moderate slope to the peripherals. The shell presents the usual shagreened 

surface, which is apparent only under the glass. 

The carapace on the midline measures 235 

millimeters in length. The width in life is estimated to be about 160 millimeters, which is 68 

per cent of the length. 

FIGURE 16.—Carapace of Hoplochelys crassa (Cope) (No. 8525, 1.7. S. N. M.). c i, C 8, Costal bones 1 and 8; C S 1, C S 4, costal scutes 1 

and 4; Ni, 2, 3, 4, p, 6, 7, neural bones 1 to 7; nu, nuchal; nu s, nuchal 

scute; py, pygal; spy, suprapygal; spy 2, second suprapygal;V 1, V5, 

vertebral scutes 1 and 5. One-third natural size. 

There are three dorsal carinae. The lateral 

keels are sharply defined, as in the type, and 

broader end forward. It is 18 millimeters long 

nata, 

and 14 millimeters wide. With the exception 

have acute crests, not obtuse, as in 

The second neural is hexagonal, with the 

or broadly rounded, as in H. laqueata. 

H. bicariof portions of the first and third, all the other 

neutrals are missing. 

The nuchal is narrowly excavated for the 

neck. Its width in front is 34 millimeters; its 

greatest width 55 millimeters; its length 37 

millimeters. 

The first peripheral is 26 millimeters high; 

the second 25 millimeters long and 28 millimeters high. The acute edge of the anterior peripherals continues across the bridge peripherals as a sharp, well-defined ridge or keel that 

eventually becomes the acute edge of the posterior peripherals. Above this lateral keel on 

the bridge the peripherals abruptly thicken to 

form a sort of roll along the shell. Above this 

thickening the peripherals send a plane portion upward to unite suturally with the costals. 

At the base of this upward prolongation of the 

peripherals runs the costo-marginal sulcus, 

which is throughout the shell well below the 

costo-peripheral suture. 

The pygal is 22 millimeters wide and 23 

millimeters high. Its free border is acutely 

edged and shallowly notched at the center. 

The sulci are narrow but well defined on account of recurring in shallow depressions in the 

bone. Where these cross the lateral keels they 

loop forward, as in the other species. 

The vertebrals were narrow. The first 

measures 40 millimeters in length and has a 

greatest width at the anterior end of only 33 

millimeters; the posterior end is 37 millimeters wide. The second vertebral is about 45 

millimeters long and 36 millimeters wide; the 

third about 42 millimeters long and 35 millimeters wide. 

The nuchal is small and trapezoidal, with the 

widest end posterior. Its width on the free 

border is 6.5 millimeters; its greatest width 11 

millimeters; its length 9 millimeters. The 

costo-marginal sulci are well below the costoperipheral suture. The intermarginal sulci are 

toward the anterior ends of the peripherals. 

Of the plastron only portions of the hyoplastra and hypoplastron remain. These elements, on the right side at the hyo-hypoplastral suture, measure 58 millimeters in width. 

It is estimated that the bridge had a width of 

about 30 millimeters. The usual intermarginals are present on the bridge. The abdominals are distant 17 millimeters from the center 

of the plastron. 

In the shape and proportions of the carapace 

this specimen most nearly approaches the type 

of H. laqueata, but it is distinguished from that 

species by the much narrower excavation of 

the nuchal for the neck, by the sharpness of 

the lateral keels as contrasted with their 

rounded crests in. H. laqueata by the presence 

on the bridge peripheral of a sharp and welldefined longitudinal keel, and by a greater 

thickening of these bones ventral to the costomarginal sulcus. The unusual narrowness of 

the first vertebral will also help to distinguish 

this species. It is quite possible that some of 
ORDER CHELONIA. 43 

the differences pointed out may be sexual characters, but at this time I know of no way of 

determining the sex in this extinct genus of 

turtles. 

Specific characters: Carapace oval, pointed 

behind; breadth of carapace 68 per cent of 

length; lateral carina well defined, sharp; 

carina crossing bridge peripherals well defined, 

sharp; excavation for neck narrow. 

Hoplochelys bicarinata Hay. 

Plate XIV, figures 1 and 2. 

Hoplochelys bicarinata Hay, U. S. Nat. Mus. Proc., vol. 

38, pp. 321-324, p1. 12, text figs. 20-23, 1910. 

The species Hoplochelys bicarinata Hay was 

founded on a somewhat fragmentary specimen 

(No. 6549, U. S. N. M.) consisting of two 

this specimen in considerable detail as being 

the first individual to portray fully the skeletal 

structure of this genus. 

This specimen was collected by J. B. Reeside, 

jr., 4 miles east of Kimbetoh, in sec. 35, T. 23 

N., R. 9 W., in the San Juan Basin, N. Mex., 

50 feet above the base of the Puerco formation. 

This would appear to be about the same 

geologic horizon as that of the type specimen 

found in the vicinity of Ojo Alamo, N. Mex. 

Specimen No. 8524, U. S. N. M., is an individual of slightly larger size than the type of 

the species but otherwise, so far as homologous 

parts are available for comparison, showing 

the closest resemblance to it. 

The bones of both the carapace and plastron 

are relatively thick, and the whole shell is of 

A B 

FIGURE 17.—Hoploehays bicarinata Hay (No. 8524, U. S. N. M.). A, Carapace: C 1, C 8, Costal bones 1 and 8; N 1, 2, 3, 4,5,6,7,8, neural 

bones 1 to 8; nu, nuchal; nu s, nuchal scute; py, pygal; spy, first suprapygal; spy 2, second suprapygal. B, Plastral view: ab, Abdominal scute; an, anal scute; ent, entoplastron; epi, epiplastron: hum, humeral scute; fem, femoral scute; bye, hyoplastron; hypo, 

hypoplastron; in mar, inframarginal scutes; pec, pectoral scute; xiph, xiphiplastron. One-third natural size. 

neurals, the complete fourth costal of the left 

side, parts of several other costals, 11 peripherals, and the greater part of the plastron. 

In the present collection a nearly perfect shell 

(No. 8524, U. S. N. M.; see Pl. XIV, figs. 1 and 

2) is identified as belonging to this species. 

This specimen is noteworthy not only as being 

the most nearly perfect example of this species 

known but also in being by far the most complete individual of the genus Hoplochelys yet 

discovered. On that account I shall describe 

compact and solid construction. The outer 

surfaces of nearly all the bones are undulating, finely shagreened but without other ornamentation. 

Viewed from above (see fig. 17, A) the 

carapace is oval, the front border is shallowly 

concave, and the back border is broadly but 

evenly rounded. The shell is highly arched 

transversely, dropping off almost vertically 

at the seventh neural to the slightly flaring 

posterior peripherals, but in front the slope is 
44 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

gradual to the widely excavated border for the 

neck. (See fig. 18.) 

The carapace in a straight line through the 

center has a greatest length of 228 millimeters 

and a greatest width of 180 millimeters. At 

the center the shell has a height of 100 millimeters. 

Along the center of the back, within the 

area of the vertebral scutes, the carapace is 

somewhat flattened and depressed below the 

surface level of the adjoining costal bones. 

There is a feeble median keel which begins on 

the first neural and whose crest rises but little 

above the surface of the bone; but immediately behind the sulcus that separates the 

second and third vertebrals there is a sudden 

of the keel toward the median line a well-defined 

groove begins at the crossing of the descending 

sulcus and runs backward, gradually disappearing before reaching the next descending sulcus. 

The nuchal bone is broadly excavated in 

front for the neck. The upper surface near 

the border has a tendency to flare upward. On 

the free border this bone is 45 millimeters 

wide. Its greatest transverse diaMeter is 67 

millimeters and its greatest length at the center 

is 35 millimeters. There are eight neurals in 

the complete series, though in the present specimen neurals 1, 5, and 8 are missing. With the 

exception of Baptemys, Hoplochelys is the only 

other genus of the family Dermatemydidae to 

have a full neural series. 

Although the first neural 

is missing in the present 

specimen, the sutural boundaries show its exact shape 

longest one of the series and 

is hexagonal, with the wider 

end directed posteriorly. 

cus 

and dimensions. As in 

and Basilemys, it is the 

AdoThe - second neural is suboval. The remaining neurals, except the eighth, are 

hexagonal, with the broad- FIGURE 18.—Carapace of Hoplochelys bicarinata Hay (No. 8524, U. 8. N. M.). Viewed from the left est end forward. The side. One-half natural size. 

depression of the bone, so that the keel stands 

up very prominently. Proceeding backward 

this keel gradually subsides, but it is again 

revived in the same manner where the sulcus 

separating the third and fourth vertebrals 

crosses the fifth neural. In a somewhat lesser 

degree this subsidence and subsequent elevation are repeated posterior to the division 

between the fourth and fifth vertebrals, where 

the ridge is much reduced, and it fades out 

altogether on the anterior end of the second 

suprapygal. 

This median keel is paralleled on either side 

by strong lateral keels that are not so acute as 

those of H. crasser but have rounded summits. 

On the side toward the midline the base of 

each lateral keel is bounded by the deep and 

sharply impressed sulcus that limits the vertebral scutes laterally. Just in front of the sulcus that descends between contiguous costal 

scutes the keel rises abruptly from the costovertebral sulcus and then rounds off into the 

general level of the costal bone. On the slope 

eighth is much reduced. 

Measurements of neurals in Hoplochelys bicarinata, in milli- meters. 

Length. Width. 

No - No. No. No. ' No. 6549 6549 8524, TT , 8524, , U.• S' U. S. U.S. U. S. N. M. N. M. N. M. N M.. (type). (type). 

1. . . .. _ 32 

2. . .._ _ 22 

3. . .... 26 

4 . . . ... 21 

5. . . ... 25 

6_ _ _ . _ _ 18.5 

7_ ... _ . a22 

8_ _ _ __ _ a 10 

20 

25 15 14 

17 

17 a 21 20 18 

18 

18 

10 

a Estimated. 

The suprapygal is small and subtriangular, 

with the widest end posterior. It is 15 millimeters long and has a greatest width of 16 

millimeters. The second suprapygal is large 

and hexagonal. It measures 27 millimeters 

antero-posteriorly along the midline and has 
ORDER CHELONIA. 45 

a greatest width of 51 millimeters. The pygal 

is largely missing in this specimen, but in all 

specimens in which it is present it shows a 

slight notch on the midline. In the present 

specimen this element has a height of about 23 

millimeters and a width of about 25 millimeters. 

There are eight pairs of costals. All except 

the third and fifth have the distal exceeding 

the proximal end in width. 

Measurements of costals in Hoplochelys bicarinata (No. 8524, 

U. S. N. M.), in millimeters. 

Width of Width of 

No. Length. proximal 

end. 

distal 

end. 

1 67 26 43 

2 77 25 29 

3 25 24 

4 90 23 29 

5 82 24 24 

6 71 20 23 

7 66 17 21 

8 50 12 21 

The costals are much thickened near their 

proximal ends where crossed by the lateral 

keel. They are closely and strongly joined 

with the peripherals by jagged sutures, but this 

union is further strengthened by the development on the distal end of strong median rib 

projections of the costal which extend down 

on the inside and are received in deep pits on 

the inner side of the peripherals. 

There are 11 pairs of peripherals. The first 

is 29 millimeters long and 29 millimeters wide 

on the free border, the second 28 millimeters 

long, the third 30 millimeters, the fourth 25 

millimeters, the fifth and sixth 24 millimeters 

each; the seventh 27 millimeters, the eighth 28 

millimeters, the ninth 30 millimeters, the tenth 

29 millimeters, and the eleventh 27 millimeters. 

The third, fourth, and fifth peripherals articulate with the hyoplastron ; the third only with 

its anterior process, which is received in a diagonal groove on the inner side. Likewise the 

sixth, seventh, and eighth peripherals unite 

with the hypoplastron. The eighth has a pit 

on the inner face of its anterior end for a 

process of the hypoplastron. All the peripherals except the first, second, and eleventh have 

pits or deep grooves on the upper and inner 

surfaces for the reception of the rib processes 

of the costals. Each peripheral has a thin 

extension rising above the costo-marginal sulcus, the absence of which in the few peripherals 

present in the type specimen of H. crassa is 

now considered a juvenile feature. 

From the slightly upturned free border of the 

third peripheral a low keel, bounded above by 

a shallow groove, continues backward across 

the bridge peripherals, merging into the free 

border on the eighth and succeeding peripherals. The free borders of the posterior peripherals present an acute edge, the whole bone 

having a tendency to flare upward. 

The sulci of the carapace are narrow but 

deeply impressed. Those bounding the vertebral scutes laterally run in deep grooves on the 

median side of the lateral keels. At the center 

of each transverse sulcus between vertebral 

scutes where the sulcus crosses the median keel 

it forms a loop forward. The vertebrals are 

long and narrow, without especial lateral expansion of their centers. 

Measurement of vertebrals of Hoplochelys bicarinata (No. 

8524, U. S. N. M), in millimeters. 

No. Length. Width. 

F 42 46 

2 _ _ _ _ 47 36 

3 47 33 

4 43 35 

5 61 a 72 

a Estimated. 

The length of the vertebral scutes as given 

in the table is taken at the side, as the absence 

of neurals 5 and 8 made it Anpractical to get 

this measurement at the center of the scute, as 

is the usual custom. Hay gives the following 

information regarding the dimensions of the 

vertebral scutes in the type: "The second vertebral scute was evidently 34 millimeters wide. 

The third was 36 millimeters wide and about 

45 millimeters long." 

The nuchal scute is small and trapezoidal, 

with the wider end posterior. On the midline 

it is 8 millimeters long, and on the free border 

it is 11 millimeters wide. 

The sulci descending on the second, fourth, 

and sixth costals are near the posterior borders 

of those bones. They also loop forward in 

crossing the lateral keels. The costo-marginal 

sulci run along well below the upper borders of 

the costo-peripheral suture, being on the posterior members at about the middle of their 

height. The intermarginal sulci descend a 

little in front of the middle of the length of the 

peripherals. 
46 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

The plastron is narrow and cruciform. It 

has a pointed posterior lobe, and both lobes are 

fixed. The plastron of specimen No. 8524, 

U. S. N. M., is but little more complete than 

that of the type specimen (No. 6549, U. S. N. 

M.), and the description here given will be 

supplemented by reference to the type specimen. From the plastron of No. 8524 there are 

missing the right epiplastron, portions of both 

the hyoplastron and hypoplastron of the right 

side, and the posterior ends of both xiphiplastra. 

The form of the plastron and its various 

bones are well shown in figure 17, B. The 

missing xiphiplastral processes were restored 

from the complete right xiphiplastron of No. 

8528, U. S. N. M., the only known specimen of 

the genus Hoplochelys in which this bone is 

perfectly preserved. 

The plastron articulates strongly with the 

peripherals by dentated sutures and by slender 

posterior and anterior processes, that are received in grooves and pits on the inner side of 

the peripherals. The hyoplastron unites with 

the third, fourth, and fifth peripherals; the 

hypoplastron slightly with the fifth and 

entirely with the sixth and seventh and the 

anterior end of the eighth. The greatest length 

of the plastron is estimated to be about 152 

millimeters, whereas Hay estimated the plastron of the type specimen to be close to 130 

millimeters. The borders of the anterior lobe 

are obtuse, having a thickness of 7 millimeters. 

Some of the principal measurements of this 

specimen as compared with the type are given 

in the accompanying table: 

Measurements of plastra of Hoplochelys bicarinata Hay, in , millimeters. 

No. 6549, No. 8524, U. S. N. M. U. S. N. M. (type). 

Length of anterior lobe 40 52 

Width of anterior lobe at base 70 87 

Length of entoplastron 26 32 

Width of entoplastron 26 29 

Width of bridge 41 40 

Width of posterior lobe at base 55 64 

The entoplastron is about as broad as long 

and is pointed in front and broadly rounded 

behind. The epiplastra are long, narrow bones 

that join by a median suture in front of the 

entoplastron. for 13 millimeters. Their posterior ends join the hyoplastra by strong 

digitating sutures for 25 millimeters, the hypoplastra for 25 millimeters, and the xiphiplastrals for about 58 millimeters. 

The width of the bridge is 40 millimeters, 

evenly divided between the hyoplastra and 

hypoplastra. 

The scutes of the plastron are described by 

Hay 1 as follows: 

The scutes of the plastron have a remarkable arrangement. On each bridge are two inframarginals, the posterior being considerably larger than the anterior, and in 

addition a small axillary scute and apparently a small 

inguinal scute. The anals and the femorals can be identified without doubt. The femorals extend forward to the 

hyo-hypoplastral suture [slightly posterior to the suture in 

both specimens]. In front of the femorals is a pair of large 

scutes that reach nearly to the middle of the entoplastron 

and overlap the hinder ends of the epiplastron. On each 

side, lying between the scutes just described and the 

inframarginals, is another large scute that extends from 

the axillary to the inguinal notch and inwardly to within 

about 18 millimeters of the midline. It seems that these 

last-mentioned scutes must be the abdominals which, as 

in Chelydra, have been crowded from the midline by the 

expansion of the pectorals and the femorals. There are 

no traces of intergulars. Gulars and humerals remain to 

be accounted for, and only a single pair remains. It seems 

probable that the gulars have been suppressed or have 

coalesced with the humerals. The arrangement of the 

carinata,

plastral scutes of this genus resembles that of 

2 except that the abdominals of Hoplochelys 

Batemys trihave 

been excluded from the midline. 

Comparative measurements of the plastral bones and scutes 

in Hoplochelys bicarinata, in millimeters. 

No. 6549, No. 8524, U. S. N. M. U. S. N. M. (type). 

Greatest length of anterior lobe 

of plastra 45 52 

Greatest width of anterior lobe 

at base 70 83 

Greatest width of posterior lobe 

at base 55 78 

Length of entoplastron 26. 5 31 

Width of entoplastron 26 27 

Width of bridge 40 40 

Hyoplastrals meet on midline for 27 27 

Hypoplastrals meet on midline 

for 26 26 

Gulars meet on midline for 30 33 

Pectorals meet on midline for 33 39 

Femoral meet on midline for 38 37 

Abdominals on the femero-pectoral sulcus distant from one 

another 35 49 

In the paper cited above Hay, in discussing 

the relationships of the species, says: 

This species differs from H. crassa (Cope) in having the 

lateral keels of the carapace broader and more obtuse. 

H. crassa also evidently had the abdominal scutes pushed 

1 Hay, 0. P., Descriptions of eight new species of fossil turtles from 

west of the one hundredth meridian: U. S. Nat. Mus. Proc., vol. 38, 

p. 324, 1910. 

2 Hay, 0. P., The fossil turtles of North America: Carnegie Inst. 

Washington Pub. 75, p. 276, figs. 347, 348, 1908, 
ORDER CHELONIA. 47 

away from the midline. The width of these at the 

inguinal notch was about 13 millimeters, whereas in 

H. bicarinata, a larger individual, these scutes are only 

5 millimeters wide. 

From H. caelata the present species differs in not having 

the bones sculptured with oblique ridges. The outer 

faces of the hinder peripherals are not flat, as they are in 

H. caelata, but more or less concave, with the free borders 

somewhat upturned. In H. caelata the hypoplastron did 

not enter the eighth peripheral. The hinder end of the 

seventh is thin, as is also the whole of the eighth. In 

H. bicarinata the anterior end of the eighth is much 

thickened and receives a process from the hypoplastron. 

The hypoplastron of H. crassa (Cope) does not pass behind 

the seventh peripheral, resembling in this respect H. 

caelata. 

An examination of specimen No. 8524, 

U. S. N. M., shows that the last statement 

is incorrect, as the eighth peripheral in H. 

crassa does receive a process of the hypoplastron. 

The characters that now appear to distinguish H. bicarinata are as follows: 

Specific characters : Carapace relatively short, 

broadly rounded behind; posterior end descending abruptly to peripherals; breadth of 

carapace 69 per cent of length; lateral carina 

well defined, obtuse; carina crossing bridge 

peripherals well defined, sharp; excavation for 

neck wide; first neural hexagonal, wider end 

directed posteriorly. 

Hoplochelys laqueata Gilmore, n. sp. 

Plate XV, figures 1 and 2. 

Type: No. 8527, U. S. N. M. Consists of 

the greater part of an articulated carapace 

and plastron, both of which have suffered loss 

of many parts of the bones comprising them. 

Collected by J. B. Reeside, jr., 1916. 

Type locality: Four miles east of Kimbetoh, 

in sec. 35, T. 23 N., R. 9 W., San Juan County, 

N. Mex. 

Horizon: Puerco formation ("50 feet above 

the base"), basal Eocene. 

chelys laqueata 

N.

the same geologic horizon as No. 8524, U. S. 

The specimen selected as the type of 

 M., here identified as pertaining to 

is from the same locality and 

HoploH. 

bicarinata, but it is at once distinguished from 

that species by the more elongated and pointed 

posterior end of the carapace. (See fig. 19.) 

The form of the carapace in H. laqueata is an 

elongated oval, slightly truncated in front and 

pointed behind. Viewed from the side (see 

fig. 20) the carapace on the posterior end is 

seen to have a gradual slope from the top to 

the peripheral border, as contrasted with the 

almost vertical descent of this region in both 

H. bicarinata and H. elongata. (See figs. 18 

and 22.) The shell is highly arched, the sides 

gradually rounding up to the lateral keels and 

not steep, as in the two last-mentioned species. 

The greatest length on the midline is about 

265 millimeters; the width is 185 millimeters ; 

the height at the center is 86 millimeters. The 

greatest width of the carapace is about 69 per 

cent of the length, whereas in H. bicarinata 

it is 78 per cent and in the type of H. elongata 

only 62 per cent. 

The bones of both the carapace and plastron 

are smooth, not having the undulating surfaces found in H. bicarinata, and the whole 

shell is of relatively lighter construction. 

There are the usual three dorsal carinae 

along the back. The lateral keels are low and 

broadly rounded, a feature that will serve to 

distinguish Hoplochelys laqueata from all other 

described species of the genus. Between the 

lateral keels the median surface of the shell appears slightly depressed below the general level 

of the carapace. 

There are eight neurals, of which the posterior part of the first and the sixth and 

eighth are missing from the type. The second 

is hexagonal, as in. H. elongata, whereas in 

H. bicarinata the second neural is oval; otherwise the neurals of these two species are very 

similar. 

Measurements of neurals in Hoplochelys laqueata (No. 8527, 

U. S. N. M.), in millimeters. 

No. Length. Width. 

1 16 

2 25 18 

3 22 16 

4 29 16 

5 22 16 

6 25 

7 . .... 21 18 

8_ _ ... 14 11 

The nuchal is largely missing, but it appears 

to have been as widely excavated for the neck 

as in H. bicarinata. 

The suprapygal and second suprapygal are 

as in H. bicarinata. The pygal is rectangular 

and has a slight median notch on the midline. 

It is 27 millimeters wide and 24 millimeters 

high. 
48 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

The peripherals in their main features are 

very similar to those of H. bicarinata, except 

that the bridge peripherals are smooth and 

not crossed by the lateral carina, in this respect 

resembling those of H. paludosa. The union 

of the plastron with the bridge and other 

peripherals, in so far as can be determined 

from the type specimen, is almost identical 

with the relation of these bones in H. bicarinata 

(see p. 45), and it appears unnecessary to repeat 

their description here. 

The sulci on the costals can be clearly traced, 

but they do not follow down well-defined 

depressions, as in H. bicarinata and other 

species. The costo-marginal sulcus runs well 

below the costo-peripheral suture, but there 

again the groove which it follows is very 

shallow as compared with those in the other 

known species. 

The only important parts of the plastron 

missing in this specimen are the posterior 

A B

FIGURE 19.—Hoplochelys laqueata Gilmore, n. sp. (No. 8527, IT. S. N. M.). Type. A, Carapace: C1, C8, Costal bones 1 and 8; NI, 2, 3, 4, 5, 6, 7, 8, 

neurals 1 to 8; nu, nuchal; py, pygal; spy, first suprapygal; spy 2, second suprapygal. B, Plastral view: ab, Abdominal scute; an, anal scute; 

ent, entoplastron; epi, epiplastron; fern, femoral scute; hum, humeral scute; hyo, hyoplastron; hypo, hypoplastron; infm, inframarginal scute; 

pec, pectoral scute; xiph, xiphiplastron. One-third natural size. 

The sulci are narrow and much more shallowly impressed than in any other known 

species of the genus. The transverse sulci 

between vertebral scutes and those bounding 

these scutes laterally run in deepened grooves. 

Where these sulci cross the median and lateral 

keels there is the usual forward loop. As in 

all the other known Puerco species of this 

genus, the vertebrals are long and narrow. 

Measurements of vertebrals of Hoplochelys laqueata (No. 

8527, U. S. N. M.), in millimeters. 

No. 

1 

2_ _ . . _ 

3_ _ . . . 

4_ _ . . 

5 

Length. Width. 

52 34 

51 31 

51 35 

73 84 

tips of the xiphiplastra and portions of both 

epiplastra. 

The plastron has the usual narrow cruciform 

shape, with pointed posterior lobe. The form 

of this part of the shell is well shown in figure 

19, B. The greatest length of the plastron is 

estimated to be about 170 millimeters, the 

length of the anterior lobe 57 millimeters, the 

width of the anterior lobe at the base 87 millimeters, and the width of the posterior lobe at 

the base 60 millimeters. The entoplastron is 

26 millimeters long and 24 millimeters wide 

and is pointed in front and broadly rounded 

behind. 

The epiplastra join on the median line in 

front of the entoplastron for 12 millimeters. 

The hyoplastra meet on the midline for 32 
ORDER CHELONIA.�
 49 

millimeters; the hypoplastra for 32 millimeters; the xiphiplastra for about 68 millimeters. The bridge has a width of 36 millimeters, of which the hyoplastron contributes 

slightly more than one-half. 

The plastral scutes have approximately the 

same arrangement as in H. bicarina,ta, though, 

as will be pointed out, their proportions are 

somewhat different. The femorals meet on the 

midline for 48 millimeters, the pectorals for 32 

millimeters, and the combined ,gulars and 

humerals for 37 millimeters. The abdominals 

of opposite sides are separated by the interposed femorals and pectorals for a distance of 

41 millimeters. 

The pectorals 

a r e relatively 

longer fore and 

aft than in H. 

bicarinata. The 

combined h u -

meral-gular 

scute in 

queata 

median line exon the 

II. laThe discovery of two specimens in the Reeside 

collection that are referable to this species 

clears up some of these details and extends the 

known geographic distribution of the species. 

The better-preserved specimen (No. 8605, 

U. S. N. M.) consists of the median and lateral 

parts of the carapace, with the greater portion 

of the plastron. The value of this specimen, 

like that of the type, is largely destroyed because of a closely adhering matrix. 

The second specimen (No. 8646, U. S. N. M.) 

consists of four peripherals, four neurals, 

numerous pieces of the costals, and fragments 

of the plastron. These bones are all free of 

tends posteri- FIGURE 20.—Carapace of Hoplochelys laqueata Gilmore, n. sp. (No. 8527, U. S. N. M.). Type. Viewed from the left orly to the pos­ side. One-half natural size. 

terior border of 

the entoplastron, whereas in II. bicarinda it 

reaches a point only slightly posterior to the 

middle of that bone. 

Hoplochelys laqueata, like all the other Puerco 

species of this genus, can be distinguished at 

once from the Torrejon forms by the relatively 

narrower neurals and vertebrals. 

Specific characters: Carapace elongated oval, 

pointed behind; posterior end 45° slope to 

peripherals; breadth of carapace 78 per cent of 

length; lateral carina not well defined, broadly 

rounded; carina crossing bridge peripherals 

faintly indicated; excavation for neck wide; 

humeral scute reaching posterior border of 

entoplastron. 

Hoplochelys saliens Hay. 

Hoplochelys saliens Hay, The fossil turtles of North America: Carnegie Inst. Washington Pub. 75, pp. 

265-266, text figs. 326-327, 1908. 

Matthew, Geol. Soc. America Bull., vol. 25, p. 383, 

1914. 

Hoplochelys saliens was established by Hay 

on the greater portion of a crushed shell covered 

by a refractory matrix that so obscured certain 

parts of the shell as to make a study of the 

detailed structure of the bones very difficult. 

the matrix and in an excellent state of preservation. Both of these specimens were 

collected in the same locality, 8 miles N. 60° E. 

of Kimbetoh, in sec. 17, T. 23 N., R. 8 W., 

San Juan County, N. Mex., in the Torrejon. 

formation. 

A comparison of the neurals of No. 8646 

with those of the type shows that these elements were incorrectly figured in the original 

description of the type specimen. The first 

neural is shown by specimen No. 8646, U. S. 

N. M., to be oval instead of quadrangular, as 

tentatively outlined by Hay. The succeeding 

neurals are relatively broad and hexagonal, 

with the wider end forward, and the posterior 

end much narrowed and convex on end, not 

wide and with straight posterior end, as Hay 

indicated. 

Measurements of neurals of Hoplochelys saliens (No. 8646, 

U. S. N. M.), in millimeters. 

No. Length. Width. 

1 38 24 

2 34 32 

3 36 34 

4 34 38 

5 

6 30 34 

115836' --I9 ----4 

50 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

It appears quite probable that, as in the 

other species of the genus, there was a complete set of eight neurals, not a reduced number, 

as indicated in the original figure of the type 

specimen. 

The lateral keels present features that appear 

to be distinctive of the species. On the external side the heavy keels drop off vertically 

to the general surface level, and, as in the type, 

along none of these keels is the bone especially 

sunken in for the passage of the intercostal 

sulcus. This specimen shows the second vertebral scute to have had a length of about 69 

millimeters and a width of 62 millimeters. The 

transverse sulcus between the first and second 

vertebrals sends a loop forward where it 

crosses the median keel posterior to the middle 

of the first neural. 

The plastron of specimen No. 8606 contributes but little to a better understanding of 

this part of the shell. It shows the sutures for 

the missing epiplastra and confirms the conclusion reached by Hay that these bones are 

missing in the type specimen. 

species described. It is to be distinguished 

from 

gata 

brals, as compared with any of the Puerco 

Hoplochelys saliens 

in having relatively wide neurals and verteH. elongata by its larger size, the wider 

Hay resembles H. donexcavation of the nuchal region, and the 

stronger development of the median and lateral 

keels. 

The characters that now appear to distinguish this species may be briefly summed up as 

follows: 

Specific characters: Largest species of the 

genus; lateral carina broad, external sides 

dropping perpendicularly to general surface 

level, not sunken where crossed by sulci; vertebrals and neurals relatively broad; excavation for neck broad. 

Hoplochelys elongata Gilmore, n. sp. 

Plate XVI, figures 1 and 2. 

Type: No. 8553, U. S. N. M. Consists of the 

greater part of an articulated carapace and 

plastron. The former lacks the proximal portions of the posterior and anterior costals and 

the posterior end of the nuchal; the latter, the 

entoplastron, epiplastron, and xiphiplastron. 

Collected by J. B. Reeside, jr., 1916. 

Type locality: Eight miles N. 60° E. of 

Kimbetoh, in sec. 17, T. 23 N., R. 8 W., San 

Juan County, N. Mex. 

Horizon: Torrejon formation, basal Eocene. 

In form the carapace of Hoplochelys elongata 

is an elongated oval, rounded in front and more 

broadly rounded behind. The sides are steeply 

arched; the top flattened. The greatest length 

on the midline is 275 millimeters; the width 170 

millimeters; the height at the center about 92 

millimeters. In size, therefore, this species is 

intermediate between H. bicarinata, from the 

Puerco, and H. saliens, from the Torrejon. 

There are the usual three dorsal carinae. 

The median keel presents a sharper and higher 

ridge posteriorly than in H. crassa, but as in 

that species it fades out on the anterior 

neurals. On either side are the heavy rounded 

keels, but as in H. saliens none of these keels 

are crossed by sunken areas where the transverse sulci cross, such as are found in H. 

crassa and H. bicarinata. 

There are eight neurals, which are hexagonal 

in shape, with the broader end forward except 

in the first. All the neurals posterior to the 

second have a median keel. The shape and 

proportions are well shown in figure 21. 

Measurements of neurals in Hoplochelys elongata (No. 

8553, U. S. N. M.), in millimeters. 

No. Length. Width. 

1 17 

2 26 22. 5 

3 27 26 

4 . 26 26 

5 23 26 

6 23.5 25 

7. 17 20 

8 . 19 18 

The nuchal, as compared with those in other 

species of the genus, is narrowly excavated for 

the neck. In front its free border is 34 millimeters wide. This bone in conjunction with 

11 peripherals and a pygal forms the rim of the 

carapace. The peripherals behind the bridge 

have a tendency to flare slightly upward and 

are acutely edged. Those in front have more 

obtuse borders. The bridge peripherals are 

crossed low down by a lateral keel, which fore 

and aft merges into the rim of the carapace. 

Above this keel the peripherals suddenly 

thicken to form " a sort of roll along the shell." 

The first peripheral is 29 millimeters long on 

the free border; the second, 31 millimeters; 

the fourth, 29 millimeters; the seventh, 32 

millimeters long and 32 millimeters high; the 

eighth, 32.5 millimeters long and 36 millimeters 
ORDER CHELONIA. 51 

high; the ninth, 31 millimeters long; the tenth, 

30 millimeters long and 36 millimeters high; 

the eleventh, 30 millimeters long. The pygal 

is 30 millimeters wide on the free border and 

28 millimeters high. 

The anterior costal plate has a, greatest width 

of about 75 millimeters; the next five pairs, a 

width of 30 millimeters or more. 

The surfaces of the bones of the carapace 

are smooth, but under the glass present a 

shagreened texture, a feature typical of the 

other species of the genus. 

The transverse sulcus between the fourth and 

fifth vertebrals crosses the eighth neural, as in 

H. laqueata. The costo-marginal sulcus runs 

below the costo-peripheral suture at about the 

middle of their height. The nuchal scute is 

subtriangular in form, with the narrow end 

forward. On the free border it measures 7 

millimeters wide; on the posterior border, 12 

millimeters. The entoplastron, epiplastron, 

and xiphiplastron are missing from the plastron • 

of this specimen. At the center the plastron 

has a greatest breadth of 120 millimeters. It 

A B 

FIGURE 21.—Hoplochelys elongata Gilmore, n. sp. (No. 8553, U. S. N. M. ). Type. A, Carapace: Cl, C5, Costal bones 1 and .5; N1,8, 3, 4,5,6,7,8, 

neural bones 1 to 8; nu, nuchal; py, pygal; spy, first suprapygal. B, Plastral view: ab, Abdominal scute; an, anal scute; ent, entoplastron; epi, epiplastron; fern, femoral scute; hum, humeral scute; hyo, hyoplastron; hypo, hypoplastron; pec, pectoral scute; xiph, xiphiplastron. One-third natural size. 

The sulci are narrow, as in H. crassa and H. 

bicarinata, and about as deeply impressed. The 

vertebral scutes are broad, as in H. saliens, a 

feature that at once distinguishes the Torrejon 

from the known Puerco species of the genus, 

(Compare figs. 17, 19, and 21.) 

Measurements of vertebrals in Hoplochelys elongata (No. 

8553, U. S. N. M.), in millimeters. 

No. Length. Width. 

1 _ 58 44 

2 55 49 

3 . 56 47 

4 53 

5 . .... 73 94 

is strongly sutured to peripherals 4, 5, 6, and 7, 

and a long tapering process extends forward in 

a groove to further strengthen this union on the 

inside of peripheral 3 and into a, pit on peripheral 8. The form of the bones preserved is well 

shown in figure 21, B. The anterior lobe is 76 

millimeters wide at the base; the posterior 

lobe, 55 millimeters. The entoplastron had a 

greatest width of about 27 millimeters. The 

hyoplastra joined on the midline for a distance 

of 33 millimeters; the hypoplastra for 34 millimeters. The greatest thickness of the hypoplastra is 16 millimeters. The least width of 

the bridge is 41 millimeters. The scutes of the 

plastron, so far as they can be observed, have 
52 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

the same arrangement as in H. bicarinata, except that the anal scutes extend anterior to the 

hypo-xiphiplastral suture. There are three 

inframarginal scutes on the bridge; each of the 

anterior two is considerably smaller than the 

posterior one. The femorals extend forward 

nearly to the hyo-hypoplastral suture. The 

triangular abdominals are excluded from meeting on the midline by the expanded femorals 

and pectorals, which join transversely between 

the abdominals for a distance of 28 millimeters. 

The pecto-humeral sulcus crosses the posterior 

end of the entoplastron, as in H. bicarinata. 

The present collection contains, in addition 

to the type, two other specimens (Nos. 8608 

and 8609, U. S. N. M.) that are sufficiently 

rounded lateral keels along the top of the carapace. From H. paludosa Hay it differs by 

having, like most other species of Hoplochelys, 

a keel crossing the bridge peripherals well 

below the costo-marginal sulcus. 

The characters which at this time will serve 

to distinguish H. elongata may be briefly 

summed up as follows: 

Specific characters: Carapace elliptical; shell 

narrow, elongated, width being 62 per cent of 

the length; lateral carinae broadly rounded; 

carinae crossing bridge peripherals well defined, 

sharp; excavation for neck narrow; vertebrals 

and neurals relatively broad; posterior end of 

carapace descending abruptly to peripheral 

border. (See fig. 22.) 

FIGURE 22.—Carapace of Hoplochelys elongata Gilmore, n. sp. (No. 8553,U. S. N. M.). Type. Viewed from the left side. One-half natural size. 

well preserved to be identified as pertaining 

to this species. Both are from the same locality 

and the same geologic horizon as the type 

specimen. 

In No. 8609 the first neural, a bone part 

of which is missing in the type, is preserved 

intact. This bone is oval, as contrasted with 

the hexagonal first neural of H. bicarinata 

Hay. It is 34 millimeters long and has a 

greatest width of 22 millimeters. In text 

figure 21, A, the missing part of this element has 

been restored after this bone. 

nata, 

median keel, and the less pronounced depresneck, the wider vertebrals, the more pronounced 

pace, the narrower notch in the nuchal for the 

Hoplochelys elongata 

Hay in the more elongate form of the caradiffers from H. bicarisions where the transverse sulci cross the lateral 

keels. From H. saliens Hay it is distinguished 

by its somewhat smaller size, the relatively 

narrower bridges and nuchal notch for the 

neck, and the less prominent median and more 

Superfamily TRIONYCHOIDEA Hay. 

Family PLASTOMENIDAE Hay. 

Genus PLASTOMENUS Cope, 1873. 

The genus Plastomenus is represented in the 

present collection by two specimens, both of 

which appear to be true members of the genus. 

As the principal characters that define this 

genus are found in the plastron—that is, the 

hyoplastra, hypoplastra, and xiphiplastra are 

closely united, usually by suture—the assignment of a species based on the carapace is 

always problematic. This remark applies 

especially to the type of Plastomenus perplexes. 

Fifteen species have been assigned to this 

genus prior to the study of the present collection, but Hay remarks that "when more complete remains shall have been discovered some 

of these species will have to be placed in other 

genera." A single Torrejon species, 

pictus Hay, was known previously. 

P. acu­
ORDER CHELONIA. 53 

A second specimen (No. 8553), consisting of 

parts of the hyoplastra and hypoplastra, from 

the same formation and locality as P. perplexus, 

certainly belongs to Plastomenus and apparently represents an undescribed species, which 

defer naming on account of its incomplete 

state of preservation. (See Pl. XXIII, fig. 2.) 

Plastomenus robustus, from the Kirtland, is 

the first member of this genus to be recognized. 

specifically from that formation. 

Plastomenus robustus Gilmore, n. sp. 

Plate XVII; Plate XVIII, figure 1. 

Type: No. 8538, U. S. N. M. Consists of the 

nearly perfect carapace, and the hyoplastron 

and hypoplastron of the right 

side. Collected by J. B. Beeside, jr., 1916. 

Type locality: About 31 miles 

southwest of Kimbetoh, near 

the south side of sec. 4, T. 22 

N., R. 10 W., San Juan County, 

N. Mex. 

Horizon: Kirtland formation 

(75 feet above the b ase). Upper 

Cretaceous. 

The carapace of Plastomenus 

robustus is subquadrangular in 

outline and is broader than 

long, the length bein,g 400 millimeters and the width 430 mill imeters. It is convex transversely, being shallowly depressed along the middle. The 

front of the shell is very slightly 

concave along the nuchal, and 

the back is widely excavated, 

as in Aspideretes beecheri Hay. 

The abruptly rounded lateral 

borders are somewhat sinuous; 

Measurements of neurals in Plastomenus robustus (No. 8538, 

U. S. N. M.), in millimeters. 

No. Length. Width. 

1 32 32 

2 45 29 

3 40 28 

4 41 26 

5 36 23 

6 29 15 

7 21 14 

The costals display nothing particularly 

characteristic. The ribs extend little if at all 

beyond the borders of the carapace. There 

are the usual eight costals. The eighth pair 

meet on the midline for their full width, a. 

the front and back borders are FIGURE 23.—Carapace of Plastomenus robustus Gilmore, n. sp. (No. 8538, U. S. N. M.). Type. 

CI, C8, Costal bones 1 and 8; Ni, 2, 3, 4,5,6,7, neural bones 1 to 7; nu, nuchal; p ne, pre- abruptly cut off at right angles to neural. One-fourth natural size. 

the upper surface. (See fig. 23.) 

The nuchal bone from side to side measures 

270 millimeters in length. At the center, 

where it is notched for the preneural, it is 47 

millimeters wide. There is a shallow sinus 

running along the middle of its anterior 

border. The preneural is as broad as long, 

measuring 37 millimeters in both diameters. 

There are seven neurals. 

distance of 65 millimeters, The seventh pair 

meet for about half their width, the forward 

halves being separated by the last neural. 

The combined eighth costals form 113 millimeters of the median posterior border, and 

their free border is convex transversely. The 

costals are relatively thick and heavy throughout but especially toward the distal end. 
54 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

The sculpture of the carapace consists of a 

network of flat-topped ridges, inclosing pits 

that are usually circular in shape. There are 

usually three of these pits in a 10-millimeter 

line, though toward the center of the shell, 

where the ridges appear to be washed off, the 

pits are shallower and smaller and have concave 

bottoms and in many places there are four pits 

in a 10-millimeter line. On the outer half of the 

costals, where the pits are largest, they are 

arranged in rows transverse to the longer 

diameter of the costals. On the outer ends of 

these bones the summits of the ridges become 

acute and the pits smaller and more irregular 

in shape and size. As in A. beecheri, the 

upper two-thirds of the sutures between the 

costals resemble seams in leather sewed with 

fine stitches. The whole surface of the nuchal 

is sculptured. 

The plastron of this specimen is represented 

by the complete hyoplastron and hypoplasFIGURE 24.—Plastral bones of Plastomenus robustus Gilmore, n. sp. 

(No. 8538, U. S. N. M.). Type. r hyo, Right hyoplastron; r hypo, 

right hypoplastron. One-fourth natural size. 

tron of the right side. The union of these two 

bones is so thorough that all traces of the 

suture has now been obliterated. The combined length of these elements at the midline 

is 158 millimeters. Their greatest width 

anteroposteriorly at the center is 237 millimeters; the width of the entire plastron across 

the bridges would be about 474 millimeters. 

Along the median suture these bones have an 

average thickness of 15 millimeters. For 120 

millimeters on either side of the midline the 

ventral surfaces of these bones are flat, but 

farther away they slope upward and outward. 

Where this upward slope begins the bone 

becomes thinner and continues so to their 

outer edges. The bridge is 79 millimeters 

wide. The posterior border of the hypoplastron between the deep notch and the 

median line shows an oblique thickened sutural 

edge for the xiphiplastron. The hinder lobe 

has a width at the base of about 250 millimeters. The outwardly directed processes 

are missing from both the hyoplastra and 

hypoplastra. 

The whole lower surfaces of these bones are 

sculptured into a network of ridges inclosing 

pits of varying shapes and sizes, nowhere 

having any regular arrangement. In a 10­

millimeter line there may be either four or five 

pits. This sculpture is well shown in Plate 

XVIII, figure 1. 

A hypoplastron. (No. 8350, U. S. N. M.) 

collected by Mr. Bauer in 1915 from the Farmington sandstone member of the Kirtland, 

which was figured by me,1 represents a very 

closely related if not identical species. It is 

considerably smaller than the hypoplastron of 

the type of Plastomenus robustus (fig. 24), and 

the sculpture differs somewhat, as may be 

seen by a comparison of the two figures. 

The closely united hyoplastra and hypoplastra, as shown in this specimen, indicate at 

once its generic assignment to Plastomenus. 

Its very large size, truncated front and back 

ends, and carapace without welts crossing the 

costals form a combination of characters in 

which it is quite unlike any of the other known 

species of this genus. Without the plastron I 

should have unhesitatingly assigned it to 

Aspideretes, and it serves to illustrate the 

great uncertainty in assigning to either of. these two genera specimens consisting only of 

the carapace. It now appears that only the 

discovery of plastra of the several species 

in each genus founded on the upper shell 

will render their generic assignment certain. 

The combination of characters which at 

this time will distinguish Plastomenus robustus 

may be stated as follows: 

Specific characters: Typically of large size; 

disk of carapace broader than long; anterior 

end truncated, posterior end broadly excavated; costals without welts; eighth pair of 

costals reduced; sculpture of carapace moderately coarse, there being three or four pits in 

10-millimeter line; sculpture of plastron somewhat vermiculate. 

1 Gilmore, C. W., Vertebrate faunas of the Ojo Alamo, Kirtland, and 

Fruitland formations: U. S. Geol. Survey Prof. Paper 98, p. 299, pl. 78, 

fig. 1, 1916. 
ORDER CHELONIA. 55 

Plastomenus torrejonensis Gilmore, n. sp. 

Plate XIX, figure 2. 

Type: No. 8543, U. S. N. M. Consists of 

six costals of the right and three of the left 

side, neurals 2 and 4, and a small fragment of 

the plastron. Collected by J. B. Reeside, jr., 

1916. 

Type locality: Eight miles N. 60° E. of 

Kimbetoh, in sec. 17, T. 23 N., R. 8 W., San 

Juan County, N. Mex. 

Horizon: Torrej on formation ("840 feet 

above base of the Puerco, in Torrejon."), basal 

Eocene. 

It is estimated that the carapace of the type 

specimen of Plastomenus torrejonensis had a 

greatest length of about 106 millimeters and a 

width across the fourth pair of costals of 67 

millimeters. The rib ends extended beyond 

the ends of the costals, but all are missing in 

this specimen. The second neural is 15 millimeters long; the fourth 12 millimeters long 

and 9 millimeters wide. The two halves of 

the fourth neural are divided by a longitudinal 

flat-topped keel. The costals have the following dimensions, the length being taken from 

the free end of the costal to the border of the 

neural and the width taken at the neural 

border: First, 22 millimeters long, 15 millimeters wide; second, 29 millimeters long, 14 

millimeters wide; third, 31 millimeters long, 13 

millimeters wide; fourth, 31 millimeters long, 

13 millimeters wide; fifth, 28 millimeters long, 

13 millimeters wide; seventh, 22 millimeters 

long, 14 millimeters wide. 

The anterior border of the first costal is 

smooth, indicating that it was not suturally 

united with the nuchal. The oblique cutting 

off of the anterior proximal corner of the first 

costal, which has a sutural edge, apparently 

indicates the presence originally of a small 

preneural bone. The surfaces of the costals 

are crossed fore and aft by four to five subparallel ridges or welts, which run from one 

end of the carapace to the other. (See Pl. 

XIX, fig. 2.) The surface is pitted everywhere except on the outer ends of the costals. 

The pits are usually in rows parallel with the 

more conspicuous ridges. There are from six 

to seven of these shallow pits in a line 10 

millimeters long. 

Originally there were eight pairs of costal 

bones, though the last pair were small. (See 

fig. 25, C 8.) The seventh pair appear to have 

been in contact on the median line for one-half 

their width. It would seem that there were 

seven neurals; the seventh was greatly reduced. 

It appears quite possible that the nuchal of 

this individual may have had no sutural connection with the anterior costals, being in 

sutural contact with the disk only through a 

small preneural that is now missing. 

In its small size, the character of the surface 

ornamentation, the presence of a number of 

FIGURE 25.—Carapace of Plastomenus torrejonensis Gilmore, n. sp. (No. 

8543, IT. S. N. M.). Type. CI, C8, Costal bones 1 and 8; N1, 2, 5,4, 

5,6, 7, neural bones 1 to 7; nu, nuchal; p ne, preneural. Three-fourths 

natural size. 

parallel welts crossing the costal bones, and 

the wide rib ends this specimen closely resembles Platypeltis serialis (Cope), Platypeltis 

trepida Hay, and Plastomenus acupictus Hay. 

The presence in specimen No. 8543 of a full 

complement of costals and evidence indicating 

the former presence of a pr neural bone shows 

that its generic affinities are with either 

Aspideretes or Plastomenus. Provisionally it 

is referred to Plastomenus until the discovery 

of more complete materials, especially of the 

plastron, shall definitely decide its proper 

disposition. 

tis trepida 

A review of the materials on which 

Hay and Platypeltis antiqua 

PlatypelHay 

were founded shows that the generic assignment 

of these species is not altogether certain. More 

complete materials may show that one or both 

should be transferred to the genus 

menus. 

Plasto­
56 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

Specimen No. 8543 is distinguished from 

Platypeltis trepida Hay by its narrower shell 

and the nonsutural union of the nuchal with 

the first costals. It resembles Platypeltis 

antiqua in the proportions of the carapace and 

the lack of the sutural articulation of the 

nuchal with the first costal, but its wider 

neurals and the lack of longitudinal welts 

crossing the costals appear to indicate specific 

distinctness. 

Plastomenus torrejonensis is distinguished 

from Plastomenus acupictus, also from the 

Torrejon formation, by the larger pits forming 

the sculpture, the smaller number of longitudinal welts crossing the costals, and the very 

much smaller seventh costal. 

FIGURE 26.—Carapace of Aspideretesreesidei Gilmore, n. sp. (No. 8537, U 

Type. C I, C 8, Costal bones 1 and 8; N I, 2, 3, 4, 6, 6, neural bones 

nuchal; p ne, preneural. One-third natural size. 

Specific characters: Disk of carapace elongated oval; nuchal not suturally united to first 

costals; longitudinal welts crossing costals; 

some of neurals keeled; six or seven pits in a 

line 10 millimeters long. 

Family TRIONYCHIDAE. 

Genus ASPIDERETES Hay, 1904. 

Five new species are here assigned to the 

genus Aspideretes, four of which are from the 

Puerco, thus doubling the number of known 

forms from that formation. 

Aspideretes reesidei Gilmore, n. sp. 

Plate XX. 

Type: No. 8537, U. S. N..M. Consists of an 

almost complete carapace. Collected by J. B. 

Reeside, jr., 1916. 

Type locality: About 4 miles east of Kimbetoh, in secs. 22 and 27, T. 23 N., R. 9 W., 

San Juan Basin, San Juan County, N. Mex. 

Horizon: Puerco formation ("50 feet above 

the base"), basal Eocene. 

The carapace of Aspideretes reesidei is subcircular (fig. 26). The shell measures 260 millimeters in length on the midline, and 255 millimeters in width across the third costals at the 

widest part. The latter measurement does not 

include the rib projections, which are 

largely missing in this specimen. The 

carapace is flattened out, but in life 

it was moderately convex transversely 

and in all probability less so longitudinally. The margins of the shell are 

scalloped, with a smooth beveled band 

that is very slightly concave and extends 

around the entire shell. In this respect it resembles A. puercensis Hay. 

The front margin of the small nuchal 

plate in the midline is shallowly concave transversely. The outline of the 

shell is broadly rounded behind, with a 

decided notch on the midline, much as 

in Aspideretes guttatus (Leidy). The 

sculpture consists of a network of flattopped ridges, which on the neurals 

and upper third of the costals inclose 

small pits of irregular shapes and sizes. 

On the distal two-thirds of most of the 

costals the ridges have more acute tops 

. S. N. M.). and assume a fore and aft direction with 

1 to 6; nu, deep valleys between. These valleys 

are divided by low transverse ridges, 

the summits of which are for the most 

part rounded and rise but little above the level 

of the valley floor. Here and there these transverse ridges rise to the height of the longitudinal 

ridges, thus inclosing pits of various shapes and 

sizes. This feature becomes more apparent 

on the front and back portions of the shell. 

There are usually five of these longitudinal 

ridges in a line 10 millimeters long. The 

median half of the sutural borders of the 

costals presents a band almost devoid of pits 

and is finely striated at right angles to the 

sutures, as in Aspideretes puercensis Hay. 
ORDER CHELONIA. 57 

The nuchal is firmly joined by its whole 

posterior border to the preneural and first 

costals. Some of its outer extremities appear 

to be missing, but the lateral extent is estimated to be about 134 millimeters and the 

antero-posterior extent is 30 millimeters. On 

the upper side the nuchal is smooth except on 

a patch in the central portion, 75 millimeters 

wide and 17 millimeters long, which has the 

sculptured surface found elsewhere on the 

carapace. Around this area the bone is 

beveled off in continuation of the beveled border 

of the rest of the carapace. The outer extremities of the nuchal are slightly damaged, 

so that their full extent can not be determined. 

There are six neural bones preceded by a preneural of good size. There are the usual number of eight costals. 

The preneural is a trapezoid, whose longest 

side, measuring 34 millimeters, articulates with 

the nuchal, while its shortest side, 16 millimeters, joins the first neural. The first five 

neurals are elongated hexagonal, with the 

broader end directed posteriorly. The sixth 

is narrow and tapers off to a point on the posterior end. 

Measurements of preneural and neurals in Aspideretes reesidei (No. 8537, U. S. N. M.), in millimeters. 

Element. Length. Width. 

Preneural 25 33 

Neural 1 26 20 

Neural 2 31 21 

Neural 3 28 19 

Neural 4 26 19 

.Neural 5 26 15 

Neural 6 24 8 

Of the costal bones the first is broadest, at 

its midlength measuring 43 millimeters fore 

and aft. The second and fifth have a greater 

distal breadth than any of the others. The 

eighth pair meet on the midline for a distance 

of only 4 millimeters. The sixth pair barely 

meet at the center, posterior to the pointed 

sixth neural. In the form of the carapace, the 

shape of the preneural, and the scalloped border 

with beveled edges this specimen resembles 

A. sagatus Hay, also from the Puerco deposits 

of New Mexico. The decided notch on the posterior median border, the shape of the nuchal, 

and the character of the sculpturing form an 

assemblage of characters not found in any other 

described species of the genus. I take pleasure 

in naming this beautiful specimen Aspideretes 

reesidei in honor of Mr. J. B. Reeside, jr., who 

was responsible for bringing together this fine 

collection of chelonian materials. 

Specific characters: Disk of carapace slightly 

longer than wide; nuchal relatively narrow 

transversely, joined by its whole length to preneural and first costals, and extending forward 

beyond the general outline of the disk; free 

ends of first costals looking strongly forward; 

notch on posterior median border of disk. 

Outer two-thirds of costals crossed by longitudinal ridges; five ridges or four valleys in a line 

10 millimeters long. 

Aspideretes vegetus Gilmore, n. sp. 

Plate XVIII, figure 2; Plate XXI. 

Type: No. 8539, U. S. N. M. Consists of 

considerable portions of the carapace and plastron. Collected by J. B. Reeside, jr., and 

party, 1916. 

Type locality: Four miles east of Kimbetoh, 

in sec. 35, T. 23 N., R. 9 W., San Juan County, 

N. Mex. 

Horizon: Puerco formation ("50 feet above 

the base "), basal Eocene. 

Although the preneural, first, fifth, and 

seventh neurals, and portions of many of the 

costals are missing from the type specimen of 

Aspideretes vegetus, for all practical purposes 

the parts preserved are distributed in such a 

manner as to give a very accurate and comprehensive idea of the structure of the entire 

carapace. (See fig. 27.) 

The carapace is oval, with the broader portion somewhat in front of the middle. It has a 

greatest length in a straight line of 215 millimeters; a width of 193 millimeters. The 

nuchal is relatively short (84 millimeters) 

transversely, reaching only to the rib of the 

first costal. At the center it measures 21 

millimeters antero-posteriorly. The front margin of this plate on the midline is slightly 

convex both longitudinally and transversely. 

Around the margin the carapace is abruptly 

beveled except on the first costals, which are 

perpendicularly truncated. 

The preneural is missing, but the sutural 

edges on the first costal and median posterior 

border of the nuchal plate clearly show that it 

was present, and also that it projected forward 
58 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

into the body of the nuchal plate, the specimen in this respect resembling Plastomenus 

oedemius Cope. All the described species of 

Aspideretes based on sufficient material show 

the union between preneural and nuchal as 

being straight, without indentation of the 

nuchal by the preneural. 

There were seven neurals, but the first, fifth, 

and seventh are missing in this specimen. 

Their principal dimensions are given in the 

accompanying table and their other characteristics are clearly shown in figure 27. 

The sculpture of the carapace consists of 

rather shallow pits, separated by ridges whose 

summits are either flat topped or rounded. 

Of these pits there are usually four in a line 10 

millimeters in length. They show only a slight 

tendency toward arrangement in rows. Along 

the middle of the carapace are a considerable 

number of parallel longitudinal ridges or welts. 

These appear most prominent on the posterior 

end of the disk, where they extend to the rim. 

(See Pl. XXI.) These ridges forward of the 

seventh costal are flat topped, and their summits are punctured with minute pits. These ridges or welts 

extend outward from the center 

well down on the costals, and 

many of them assume a diagonal course in relation to the 

longer axis of the shell. The 

ribs projected well beyond the 

borders of the carapace, though 

all of these ends are missing on 

this specimen. The free border 

of the seventh costal is especially narrow, as in A. sagatus 

Hay, measuring only 20 millimeters; the eighth pair of costals contribute 91 millimeters 

to the posterior border of the 

carapace. They meet on the 

midline for a distance of 43 

millimeters. 

Of the plastron there are 

preserved the greater portion 

of the right hyoplastron, a fragment of the left, and nearly all 

of both the hypoplastra. The 

xiphiplastron is represented by 

two or more fragments. (See 

FIGURE 27.—Carapace of Aspideretes vegetus Gilmore, n. sp. (No. &539, U. S.N.M.). Type. Ci, fig. 28.) 

C8, Costal bones 1 and 8; XI, 2,8, 4,5,6, 7, neural bones 1 to 7; nu, nuchal; p ne, preneural• The hyoplastron and hypo- One-half natural size. 

Measurements of neurals in Aspideretes vegetus (No. 8539, 

U. S. N. M.), in millimeters. 

GreatElement. Length. est 

width. 

Preneural__ a 21 

Neural 1 a 18 _ _ _ _ _ _ 

Neural 2 24 15 

Neural 3 21 13 

Neural 4 18 13 

Neural 5 a 20 

Neural 6 16 9 

Neural 7 9 

a Estimated. 

plastron j oin by a straight suture 

for a distance of 90 millimeters. Along this suture the bone ranges from 5 to 7 millimeters in 

thickness. The narrowest part of the bridge is 

estimated to have been about 45 millimeters 

in width, of which the hyoplastron contributes 

15 millimeters, the hypoplastron making up 

the difference. The lower surfaces of the plastral bones are covered by an ornamentation 

different from that of the carapace, consisting 

of a series of short bent ridges, few of which 

inclose distinct pits. The character of this 

sculpture is well shown in Plate XXI. 
ORDER CHELONIA. 59 

In the oval form of the carapace with the 

widest part in front of the middle and the 

presence of longitudinal welts this specimen, 

it would seem, should be referred to the genus 

Plastomenus, but because of the distinct 

median separation of the two halves of the plastron and the presence of a preneural it should 

according to the accepted definition be referred to the genus Aspideretes. This species 

most closely resembles A. ellipticus Hay, also 

from the Puerco of New Mexico, but it is 

readily distinguished from that species by 

differences in the shape of the carapace, and 

the nuchal and preneural bones. The ornamentation will serve to separate the species, 

and the presence of welts in the present speciType locality: Four miles northwest of Kimbetoh, in secs. 22 and 27, T. 23 N., R. 9 W., 

San Juan County, N. Mex. 

Horizon: Puerco formation ("50 feet above 

base"), basal Eocene. 

The damaged condition of the anterior portion of the carapace of the type specimen of 

Aspideretes quadratus makes the determination 

of the bones of this part of the shell somewhat 

uncertain. There appears to be a preneural 

bone present, and on that account I refer the 

species to the genus Aspideretes, but the acquisition of better preserved material may later 

show the absence of the preneural bone, in 

which event the genus Amyda would probably 

be its proper assignment. 

FIGURE 28.—Plastron o Aspideretes vegetus Gilmore, n. sp. (No. 8539, U. S. N. M.). Type. r hyo, Right hyoplastron; r hypo, right hypoplastron; 1 xiph, anterior portion of left xiphiplastron. One-half natural size. 

men will also be of assistance in identifying 

subsequently discovered specimens. 

The characters relied on at this time to distinguish this species may be summed up as 

follows: 

Specific characters: Disk of carapace oval in 

outline; entire upper surface of nuchal sculptured; joined by whole length to preneural and 

first costals; notched on median posterior 

border for preneural; costals crossed by numerous longitudinal welts; sculpture consisting of shallow rounded pits, usually four in 

a 10-millimeter line; plastron with twisted 

ridges. 

Aspideretes quadratus Gilmore, n. sp. 

Plate XXII. 

Type: No. 8545. U. S. N. M. Consists of the 

carapace, lacking the nuchal and distal portions of the costals of the left side. Collected 

by J. B. Reeside, jr., 1916. 

The quadrangular form of the carapace has 

suggested its specific name. Originally it had 

a length of about 330 millimeters and a breadth 

of at least 370 millimeters, which does not take 

into account the extension of the ribs beyond 

the ends of the costal plates. The shell proper 

is therefore wider than long. The right half 

of the carapace is nearly perfect (see Pl. 

XXIII), lacking only the anterior border of 

the first costal and the rib ends. The nuchal 

and preneural bones are not recognizable, even 

though portions of both are probably present. 

Measurements of neurals in Aspideretes quadratus (No. 


8545, U. S. N. M.), in millimeters. 


No. Length. Width. 

34 
 1 

2�
41 


3 38 
 26


4 34.5 
 24


5 31 
 23.5


6 28 
 17


7 18.5 
 17

60 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

There are seven neurals of the usual hexagonal shape. The most posterior one is considerably reduced. (See Fig. 29). 

There are eight costals, all of which increase 

greatly in width toward their distal ends. The 

fifth is the widest of the series. It measures 

80 millimeters fore and aft at the outer extremity. The seventh and eighth pairs of 

costals join on the median line. The eighth 

themselves in rows more or less parallel to the 

margins of the carapace. The chief features 

of the sculpture are well shown in Plate XXII. 

Aspideretes quadratus is at once distinguished from all the other Puerco representatives of this genus, including A. nassau Hay, 

in having the disk of the carapace wider than 

long. It appears to resemble most nearly A. 

subquadratus Lambe,' from the Belly River 

formation of Alberta, but the much 

greater size of the present specimen, 

the change in contour of the anterior end beginning with the second 

costal, and a much less pronounced 

tendency of the sculpture to form 

continuous grooves or channels indicate its distinction from that species. It may be diagnosed as follows: 

Specific characters : Disk of carapace broader than long; posterior 

border truncated and broadly concave transversely; lateral border 

turning in abruptly toward the center on middle of second costal; from 

three to five pits in a 10-millimeter 

line. 

Aspideretes perplexus Gilmore, n. sp. 

Plate XIX, figure I. 

Type: No. 8532, U. S. N. M. 

Consists of the carapace lacking the 

FIGURE 29.—Carapace of Aspideretes quadratus Gilmore, n. sp. (No. 8545, U. S. N. M.). nuchal, the seventh neural, and 

Type. Cl, C8, Costal bones 1 and 8; N1,2,3, 4, 5,6,7, neural bones 1 to 7; p ne, pre- portions of the first costals. Col- neural. One-fourth natural size. 

pair contributes 95 millimeters to the median 

part of the posterior border and meet on the 

median line for a distance of 38 . millimeters. 

All the costal borders are smooth and beveled 

off rather gradually along the sides but become 

more abrupt on the posterior end. 

The hinder end of the carapace is slightly 

sharp ridges that are narrower than the pits. 

deretes quadratus 

concave transversely. The sculpture of 

The pits are of all shapes and sizes, though 

angularly rounded pits predominate. They 

consists of pits surrounded by 

Aspiare small on the central part of the disk, 

there being from four to five pits in a 10-millimeter line. The -pits increase in size 

toward the distal ends of the costals, where 

there are usually three pits in a 10-millimeter 

line. There is only a slight tendency on some 

of the median costals for the pits to arrange 

lected by J. B. Reeside, jr., 1916. 

Type locality: Four miles east of Kimbetoh, 

in sec. 35, T. 23 N., R. 9 W., San Juan County, 

N. Mex. 

Horizon: Puerco formation ("50 feet above 

the base"), basal Eocene. 

The specific name perplexus is applied to a 

specimen that is with doubt referred to the 

genus Aspideretes, as it could with almost 

equal propriety be assigned to Plastomenus, and 

its true generic assignment must await the discovery of the plastral bones. The presence of 

seven costals appeared at first to indicate its 

affinities with Platypeltis, but the subsequent 

recognition of a distinct preneural precludes 

its assignment to that genus. 

1 Lambe, L. M., On new species of Aspideretes from the Belly River 

formation of Alberta, with further information regarding the structure 

of the carapace of Boremys pulchra: Royal Soc. Canada Trans., vol. 8, 

pp. 11-13, 1914. 
ORDER CHELONIA. 61 

The individual is a relatively small one. 

The greatest length of the carapace is estimated to have been about 180 millimeters; 

the width of the disk in a straight line is 152 

millimeters. In outline the shell is elliptical, 

with a broad, shallow notch on the median 

posterior border. The lateral borders of the 

carapace are undulating, as shown. in figure 30. 

The rib ends project beyond the disk an undetermined distance, as none are perfectly 

preserved. 

The nuchal is missing. The preneural is a 

small, thin, angularly rounded bone. 

Following it are six neurals, the posterior one of which is missing. These are 

relatively narrow. 

Measurements of neurals in Aspideretes perplexus (No. 8532, U. S. N. M.), in millimeters. 

No. Length. Width. 

Preneural 16 16 

Neural 1 25 13 

Neural 2 25 13 

Neural 3 22. 5 12 

Neural 4 21 10 

Neural 5 20 

Neural 6 13 

There are seven costals present; the 

eighth pair seems to have entirely disappeared. The first costal has a width 

of 31 millimeters. The sixth pair join 

on the midline for about half their 

width. The seventh pair join on the 

midline for their whole width, a distance 

of 16 millimeters. 

known species of Aspideretes have a full complement of these bones, the eighth pair are 

usually much reduced in size, whereas in most 

species of Plastomenus they are of robust 

development. 

Aspideretes perplexus may be distinguished 

by the following characters : 

Specific characters : Carapace with seven pairs 

of costals; seventh pair considerably reduced; 

notch on median posterior end; sculpture of 

medium coarseness, five or six pits in a 10­

millimeter line. 

The ornamentation of the carapace FIGURE 30.—Carapace of Aspideretes perplexus Gilmore, n. sp. (No. 8532, U. S. 

N. M.). Type. C 1, C 7, Costal bones 1 and 7; N 1,2, 3, 4, 5,6, neural bones consists of ridges inclosing pits, all of 1 to 6; p ne, preneural. One-half natural size. which are wider than the ridges. There 

are from five to six pits in a line 10 millimeters long. Many of these pits are angular in 

shape, but hardly any are arranged in definite 

rows. The ridges have sharp summits on the 

outer ends of the costals but become wider and 

more rounded toward the center of the carapace. 

On the outer ends of several of the costals many 

of the ridges run fore and aft, thus inclosing elongate valleys of irregular shapes and sizes. The 

outer edges of the costals are steeply beveled. 

deretes 

reduction of the seventh pair. While all the 

the absence of the eighth pair of costals and the 

This species is assigned to the genus 

rather than to Plastomenus, because of 

AspiAspideretes sagatus Hay. 

Plate XXIII, figure 1. 

Aspideretes sagatus Hay, The fossil turtles of North America: Carnegie Inst. Washington Pub. 75, pp. 497, 

498,, pl. 93, figs. 1-3, text fig. 652, 1908. 

Specimen No. 8554, U. S. N. M., collected by 

J. B. Reeside, jr., 8 miles N. 60° E. of Kimbetoh, San Juan County, N. Mex., in sec. 17, 

T. 23 N., R. 8 W., " 840 feet above the base of 

the Puerco, in the Torrej on formation," is 

provisionally referred to Aspideretes sagatus 

Hay. This species was founded on a well-
62 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

preserved carapace from the Puerco deposits 

of New Mexico. 

The present specimen consists of the right 

half of the carapace, a portion of the nuchal 

and first costal of the left side, the preneural, 

and numerous fragments. The plastron is 

represented by a nearly perfect right hypoplastron and a portion of the end of the right 

hyoplastron. As these are the first plastral 

bones of this species to be found it appears 

important that they should be described and 

figured. 

The hypoplastron, like the bones of the 

carapace, is thick and heavy. At the center 

The sculpture consists of a network of 

ridges which inclose pits of irregular size and 

form. Most of the pits are of somewhat 

greater diameter than the ridges which inclose 

them. The pits become more uniform in size 

on the inner half and at the same time gradually grow fainter and fainter until on the 

median fourth the surface is without sculpture. 

The inner end is broadly beveled off. 

The inner or median end of the right hyoplastron has a fore and aft width of 59 millimeters. This end, as in the hypoplastron, is 

beveled off to a subacute edge along the superior border. The form of the end of this bone 

is well shown in Plate XXIII, 

figure 1. 

A second specimen (No. 

8652, U. S. N. M.), consisting 

of the almost complete hypoplastron of the right side, from 

the same locality as the specimen described above, is here 

identified as pertaining to this 

same genus and species. It 

differs from No. 8554 in having 

a broader inguinal notch and 

in some other details of form. 

The carapace of specimen No. 

8554,U. S. N. M., agrees in most 

particulars very closely with 

the type as described by Hay. 

The sculpture, however, is 

somewhat different toward the 

distal ends of the costals, where 

FIGURE 31.—Right half of the plastron of Aspideretes sagatus flay (No. 8554, U. S. N. M.). many of the ridges, instead of r hyo, Right hyoplastron; r hypo, right hypoplastron. Two-thirds natural size. 

of the suture with the hyoplastron the thickness is 13 millimeters. , One border of the 

notch for the xiphiplastron remains. (See 

fig. 31.) 

Measured across the narrowest part the 

hypoplastron is 26 millimeters wide; its transverse measurement is about 122 millimeters. 

On the outer end anterior to the lateral 

processes the sculpture on the surface stops 

about 9 millimeters short of the border and 

the thickness of the bone is reduced one-half 

by the abrupt depression of the surface, which 

beyond the depression is without sculpture and 

terminates in a subacute border, much as in 

A. puercensis Hay. The inguinal notch is 

rather angular as contrasted with the broadly 

curved notch of most other species of the genus. 

breaking up into tubercles, 

grow broader than the pits and assume a fore 

and aft direction. This feature is especially 

pronounced on costals 2, 3, 4, and 5. More 

perfect specimens may show that this form belongs to a distinct species, but for the present its 

close resemblance in all important particulars 

indicates that its closest affinities are with A. 

sagatus Hay. 

Genus AMYDA Oken. 

The genus Amyda is represented in the present collection by a single specimen from the 

Puerco formation. This specimen extends 

slightly the geologic range of this genus in the 

West, as prior to this time its most ancient 

known occurrence was in the Wasatch, though 

on the Atlantic slope specimens referred to 

Amyda are found in Cretaceous deposits. 
ORDER CHELONIA. 63 

Amyda eloisae Gilmore, n. sp. 

Plate XXIV. 

Type : No. 8540, U. S. N. M. Consists of a 

nearly complete carapace. The more important parts missing are the middle portion of 

the nuchal and the distal third of the left first 

costal. Collected by J. B. Reeside, jr., and 

party, 1916. 

Type locality: About 21 miles east of north 

of Kimbetoh, in sec. 19, T. 23 N., R. 9 W., San 

Juan County, N. Mex. 

Horizon: Puerco formation ("50 feet above 

the base "), basal Eocene. 

The specimen here described is of interest as being the first recognizable member 

of the genus Amyda to be found in the 

Puerco formation. 

The carapace (Pl. XXIV) is broad and 

uniformly arched from side to side. The 

front margin appears to have been broadly 

rounded, the rear broadly and squarely 

truncated. The greatest length of the 

carapace at the center was about 237 

millimeters; its greatest width in a straight 

line 243 millimeters. Measured over the 

curve of the shell its greatest width is 274 

millimeters. The bones are rather thick 

and heavy at the sutural borders; near 

the ends of the costals they are from 8 to 

10 millimeters thick, and through the ribs 

the thickness is 12 millimeters. The lateral borders are sinuous. As in Aspideretes 

grangeri, the upper layer of the carapace 

overhangs the middle layer, so that a gutter 

The whole top of this bone appears to have 

been sculptured. There are seven neurals, and 

these decrease in size from the first to the last. 

The first is 34 millimeters long and 18 millimeters wide, the second 28 millimeters long 

and 17.5 millimeters wide; the third 26 millimeters long and 17 millimeters wide; the fourth 

15 millimeters long. The seventh is missing, 

but the surrounding bones show it to have 

been reduced in size, as shown in figure 32. 

The eight pairs of costals are small and join 

one another on the midline. Their free ends 

form about 44 millimeters of the median 

posterior border. 

FIGURE 32.—Carapace of Amyda eloisae Gilmore, n. sp. (No. 8540, U. S. N. M.). runs around the edge of most of the cara- Type. C 1, C 8, Costal bones 1 and 8; N 1, 2, 3, 4, 5, 6, 7, neural bones 1 to 

pace. 7; nu, nuchal. One-third natural size. 

The ornamentation of the carapace is 

fairly uniform in character and is made up of a 

network of narrow, sharp ridges that ramify 

and inosculate so as to inclose small sunken areas 

of irregular shape and size. Most of the inclosed areas are wider than the ridges which 

inclose them. Toward the center and front of 

the shell the pits become smaller and shallower 

and the apexes of the ridges more rounded. 

The apexes of many of the ridges are lifted into 

sharp points, especially at the angles. There 

are from four to five pits in a line 10 millimeters long. The nuchal joins along its entire 

posterior margin with the first costals and 

neural. It is estimated to have had a greatest 

transverse extent of 142 millimeters and an 

anteroposterior extent of about 42 millimeters. 

This species resembles Amyda salebrosa Hay 

in the general shape of the carapace and in its 

ornamentation but is distinguished from that 

species by its much smaller size, by the channeled borders as contrasted with the beveled 

rim of A. salebrosa, and by having the greatest 

width posterior to the middle. 

Amyda eloisae is the most ancient member 

of the genus yet to be discovered in the Rocky 

Mountain region, though in the Atlantic region 

representatives of the genus have been found 

in the Cretaceous. It is dedicated to my 

eldest daughter, Miss Eloise Elizabeth Gilmore. 

Specific characters: Disk of carapace 

slightly broader than long; sculpture four to 

five pits in 10-millimeter line, irregular in 
64 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

character; greatest width slightly posterior to 

middle; nuchal more than half the width of 

the carapace. 

Order DINOSAURIA. 

In addition to the notable series of turtle 

remains described in the preceding pages, the 

present collection contains a number of incomplete dinosaurian specimens that despite their 

fragmentary condition contribute important 

facts to our knowledge of the geographic and 

geologic distribution of these animals. 

The armored dinosaurs are represented by 

fragmentary remains from the Kirtland and 

Ojo Alamo formations, and thus I am able to 

record for the first time their presence in the 

Ojo Alamo. The horned dinosaurs or Ceratopsia are represented by specimens showing 

the presence in the Kirtland of the genus 

Ceratops? or a very closely related form. 

Duck-billed dinosaurs or trachodont specimens in the collection, also from the Kirtland 

formation, show that both the crested and noncrested members of this group are present. 

Furthermore, for the first time remains of a 

crested trachodont have been discovered south 

of northern Montana, where they occur in the 

Judith River and Two Medicine formations. 

Suborder PREDENTATA Marsh. 

Family HADROSAURIDAE Cope. 

Because of the great number of trachodont 

dinosaurs already described, and especially 

because of the paucity of our knowledge concerning many of them, any attempt to identify speOies or even genera from fragmentary 

materials is hazardous. For this reason no 

attempt has been made to identify generically 

any of the trachodont specimens in the present 

collection. Their chief importance is in furnishing strong if not conclusive corroborative 

evidence as to the Montana age of the Kirtland formation, shown by the presence of a 

specimen having an ischium with a footed 

distal extremity and another specimen with 

an ischium terminated by a blunt rounded 

end, thus indicating the presence of the crested 

and noncrested types of trachodonts, which 

elsewhere are found associated only in formations of the Montana group. On the above 

differences Brown 1 has proposed the division 

1 Brown, Barnum, Corthyosaurus casuarius, a new crested dinosaur 

from the Belly River Cretaceous, with provisional classification of the 

family Trachodontidae: Am. Mus. Nat. Hist. Bull., vol. 33, pp. 564-565, 

1914. 

of the family Trachodontidae into the two 

subfamilies Trachodontinae,2 comprising those 

having a skull without a crest, and Saurlophinae, comprising those with a crest. 

Subfamily HADROSAURINAE Lambe. 

The subfamily Hadrosaurinae is represented 

in the Kirtland and Ojo Alamo formations by 

specimens recognized by Brown as belonging 

to the genus Kritosaurus. Reeside collected a 

specimen that belongs to this subfamily and 

possibly to Kritosaurus, 21 miles south of west 

of Kimbetoh, San Juan County, N. Mex., in 

sec. 3, T. 32 N., R. 10 W., 330 feet above the 

base of the Kirtland formation. 

This specimen (No. 8628, U. S. N. M.) consists of the poorly preserved but articulated 

sacrum of 10 vertebrae, four dorsals, 2 caudals, 

the right pubis complete and a portion of the 

left, the greater part of one ischium, the 

preacetabular portion of the ilium, both humeri, 

and several ribs. Unfortunately this specimen can not be compared with the type of 

Kritosaurus, which was based largely on a 

skull and lower jaws. 

Subfamily SAURLOPHINAE Brown. 

The presence of a member of the subfamily 

Saurlophinae is indicated by the preservation 

of the greater part of an ischium from the right 

side, which shows a distal end terminating 

in a footlike extremity. Ischia of this style 

are associated only with the skulls having a 

crest. A single tall spinous process and a 

phalangial element of the front foot are the 

other bones of this specimen collected. Mr. 

Reeside tells me, however, that more of the 

skeleton remains in the field and that lack of 

time prevented its collection. It was found 

4 miles west of Kimbetoh, in sec. 34, T. 23 N., 

R. 10 W., San Juan County, N. Mex., 380 feet 

above the base of the Kirtland formation. 

Family CERATOPSIDAE Marsh. 

Genus CERATOPS March, 1888. 

Ceratops sp. 

Plate XXV, figures 1 and 2. 

The bone (No. 8604, U. S. N. M.) figured on 

Plate XXV, figures 1 and 2, is the median bar of 

Lambe has adopted the provisional classification of this group of the 

Dinosauria proposed by Brown (see Ottawa Naturalist, February, 1918, 

p. 138) and shows that the family term Hadrosauridae, which has 

priority by several years over Trachodontidae, must be revived, especially as the validity of the genus Hadrosaurus is recognized. The 

subfamily designation in turn is therefore changed to Hadrosaurinae. 
ORDER DINOSAURIA. 65 

the frill of a fenestrated cerilttopsian dinosaur. 

It was collected by Messrs. Reeside and Clark 

3i miles south of west of Kimbetoh, near the 

south side of sec. 4, T. 22 N., R. 10 W., San 

Juan County, N. Mex., 75 feet above the base 

of the Kirtland formation. The very close 

resemblance of this specimen, both in size and 

in form, to the homologous element from the 

Belly River formation described and figured 

by Lambe' as Monoclonius belli 2 leaves no 

doubt as to their close relationship. In the 

complete skull this bar forms the median part 

of the frill and separates the large fenestrae 

on either side. On account of the close resemblance of this specimen to the Belly River 

form, it is provisionally referred to the genus 

Ceratops, the genotype of which is from the 

Judith River formation of Montana. 

Regardless of the correctness of the present 

generic identification, it represents a stage of 

development in the ceratopsian Dinosauria 

that has been found only in the Judith River 

and Belly River formations, and its discovery 

in the Kirtland substantiates the earlier conclusion3 that this formation is not later than 

Montana in age. 

A second specimen, a considerable portion of 

a right squamosal, was collected 31 miles south 

of west of Kimbetoh, N. Mex., near the southeast corner of sec. 4, T. 22 N., R. 10 W., 115 

feet above the base of the Kirtland formation. 

The small size and the shortness of this bone 

make it quite probable that it also pertains 

to the genus Ceratops. 

Ceratopsian, genus and species undetermined. 

A very fragmentary skull was collected in 

Barrel Springs Arroyo, about 1 mile southwest 

of Ojo Alamo store, San Juan County, N. Mex., 

10 to 12 feet above the base of the Ojo Alamo 

sandstone. From the great number of fragments a considerable part of the posterior end 

of what appears to be the median or dermosupraoccipital was pieced together. Although 

this large fragment is not sufficiently characteristic to indicate the generic affinities; it is of 

1 Lambe, L. M., On Vertebrata of the Mid-Cretaceous of the Northwest 

Territory; pt. 2, Contr. Canadian Paleontology, vol. 3, p. 66, p1.20, figs. 1 

and 2, 1902. 

trosaurus, 

and 

earlier described 

Lambe in a subsequent article refers this form to the genus 

Gilmore, C. W., Vertebrate faunas of the Ojo Alamo, Kirtland, 

Fruitland formations: U. S. Geol. Survey Prof. Paper 98, p. 281, 

whereas Brown now regards it as synonymous with the 

Ceratops. 

Cen1916. 

115836°-19-5 

interest as showing the presence here of a 

ceratops, Ceratops, 

openings are apparently smaller than in ether 

of the genera mentioned above. In all probament shows a fenestrated frill in which the 

ceratopsian which is distinct from either 

or Monoclonius. This fragTribility it represents an undescribed form. 

Family SCELIDOSAURIDAE Huxley. 

Genus and species undetermined. 

Plate XXVI, figure 2. 

A left scapula (No. 8571, U. S. N. M.) was 

collected by J. B. Reeside, jr., in Barrel Spring 

Arroyo, about 1 mile southwest of Ojo Alamo 

store, San Juan County, N. Mex., 10 to 12 feet 

above the base of the Ojo Alamo sandstone. 

This isolated bone belongs to one of the 

armored dinosaurs and is of special interest at 

this time in being the first bone of a representative of this group to be found in the Ojo 

Alamo formation. 

The scapula is very short and massive 

throughout. There is a prominent acromion 

process, a very wide end contributing to the 

formation of the glenoid socket, and a thick, 

heavy blade that is rounded off on its upper 

extremity. The presence of a well-developed 

acromion process and the relative shortness of 

the bone distinguish it from all the known members of the Ankylosauridae, which are without 

such a process. In order to determine if possible its true affinities, the specimen was sent 

to Mr. Barnum Brown, of the American Museum of Natural History, New York, and he 

very kindly compared it with the excellent 

armored-dinosaur material in that museum. 

Under date of Janury 30, 1917, he wrote as 

follows: 

The scapula is that of an armored dinosaur closely related to if not the genus Hoplitosaurus, and I would assign 

it provisionally to that genus. * * * Your specimen 

differs from a Hoplitosaurus scapula in the American 

Museum in that it has less dorso-ventral curvature, the 

blade is thicker, and the distal end is not broadly expanded, although the terminal border is somewhat broken. 

The large acromion process is similar in both, and the 

coracoid border is likewise extensively developed. 

I have carefully compared the present specimen with the proximal half of the scapula of 

the genotype of Hoplitosaurus marshi (No. 

4752, U. S. N. M.) and find differences that 

would indicate they are in all probability 

generically distinct, though I believe their lam-
66 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

ily attributes will be found to be the same. 

Provisionally, therefore, I refer it to the family 

Scelidosauridae until such time as the discovery of additional material shall disclose its true 

relationships. This bone undoubtedly represents an undescribed form, but on account of 

the meagerness of the material I defer naming it. 

plates, with many fragments, was collected by 

the Reeside party about 1 mile southwest of 

Ojo Alamo store, in Barrel Spring Arroyo, 10 

to 12 feet above the base of the Ojo Alamo 

sandstone. These bones in all probability pertain to the same kind of an animal as the 

scapula previously described, which was found 

a quarter of a mile distant from this locality. 

FIGURE 33.—Dermal plates of an armored dinosaur (No. 8610, U. S .N. M.) from the Ojo Alamo formation. Two-thirds natural size. 

Some of the more important dimensions of 

the scapula under discussion are: Greatest 

length from posterior border of glenoid cavity 

to upper end of blade, 320 millimeters; greatest width of blade, 120 millimeters; least 

width, 95 millimeters; greatest transverse 

width of proximal end, 120 millimeters; thickness of shaft at center, 48 millimeters; thickness of blade at upper end, 29 millimeters. 

A second specimen (No. 8610, U. S. N. M.), 

consisting of a number of dermal scutes or 

The scutes are comparatively thick, flattened 

plates of various sizes and shapes. Some have 

low dorsal ridges or carinae asymmetrically 

placed; others present only a slightly raised 

rounded center. (See fig. 33.) Several show 

by their smooth rounded edges that they existed as independent plates, but the greater 

number have sutural edges, indicating that 

they were closely united into a carapace-like 

covering. Scutes of this type are probably 

from the skin above the pelvic region, where 
ORDER CROCODILIA. 67 

they must have formed a pelvic shield much 

as in Polocanthus and Stegopelta. The close 

resemblance of the largest plate in this series 

with those found attached to the ilium in the 

genotype of Stegopelta is well shown by a comparison of figure 33 with Plate XXVI, figure 1, 

which shows the largest scute preserved, measuring 195 millimeters in one diameter and 182 

millimeters in the other. 

A third specimen in this same collection 

(No. 8611, U. S. N. M.), consisting of several 

plates, was found 1 mile south of Ojo Alamo, 

in Barrel Springs Arroyo, 3 to 8 feet above 

the base of the Ojo Alamo sandstone. It includes a few fragmentary scutes with sutural 

edges similar to those found with No. 8610, but 

in addition there are several thicker, heavier 

plates that are without dorsal ridges and have 

but few vascular markings. 

Some of the dermal scutes of these specimens show a marked resemblance to those of 

Stegopelta, from the Colorado formation, but, 

unfortunately, the scapula of that genus is unknown, so that a comparisOn of these bones 

can not be made at this time. As suggested 

above, this material may represent an undescribed form, but as there are no less than 

eight described genera of armored dinosaurs 

known from North America, all but three of 

which are based on scanty materials, it seems 

best not to burden the literature further with 

names. 

These armored dinosaurs have a wide vertical range, and when the several described 

forms are fully known they should furnish a 

most interesting chapter in dinosaurian development. 

A list of the described American species and 

the formations in which they occur is given 

below. 

Ankylosaurus magniventris Brown _ _Lance (Hell Creek 

beds). 

Ankylosaurid dinosaur (undescribed).Edmonton. 

Europlocephalus tutus Lambe Belly River. 

Palaeoscincus costatus Leidy Judith River. 

Scelidosaurid dinosaur (undescribed) Ojo Alamo. 

Scelidosaurid dinosaur (undescribed) _ Kirtland. 

Hierosaurus sternbergii Wieland Niobrara. 

Nodosaurus textilis Marsh Benton. 

Stegopelta landerensis Williston . Benton. 

Hoplitosaurus marshi (Lucas) ... Lakota. 

Priconodon crassus Marsh. Arundel (Potomac). 

Scelidosaurid dinosaur (undescribed).Cloverly. 

Stegosaurus (several species) Morrison. 

Suborder. THEROPODA. 

Family MEGALOSAIIRIDAE. 

Genus and species undetermined. 

A few fragmentary vertebrae of a very large 

carnivorous dinosaur were collected by J. B. 

Reeside, jr., in Barrel Spring Arroyo, west of 

the road, 1 mile south of Ojo Alamo, N. Mex., 

3 to 8 feet above the base of the Ojo Alamo 

formation. This specimen is too fragmentary 

to be identified and is of interest only as 

showing the occurrence in the Ojo Alamo 

formation of a large carnivorous dinosaur of 

the proportions of Tyrannosaurus. During the 

preceding season carnivorous dinosaur teeth 

were found by the United States Geological 

Survey party under C. Max Bauer in the same 

locality 1 and practically at the same geologic 

horizon. 

Order CROCODILIA. 

Fossil crocodile remains are present in both 

the Puerco and Torrej on formations, although 

to judge from the present collection they are 

more abundant in the Puerco, there being 15 

specimens from that formation, whereas there 

are only three from the Torrejon. 

All these specimens are extremely fragmentary, and in the present state of our knowledge 

regarding the extinct crocodiles none are 

identifiable. Cope 2 in 1885, on inadequate 

species, though I doubt the ability of anyone 

lianus, 

material, named one species, •

quite probable that some of the specimens in 

the present collection may pertain to that 

from the Puerco formation, and it is 

Crocodilus staveto identify specimens with a species founded 

on a single tooth. 

The relatively small size of the dermal scutes 

and vertebral centra preserved indicates that 

the individuals represented were comparatively 

small. 

Those specimens in the present collection 

from the Puerco formation were found 4 miles 

northwest of Kimbetoh, in sec. 27, T. 23 N., R. 

9 W., San Juan County, N. Mex., 50 feet above 

the base of the formation. Those from the 

Torrejon formation were found near by, in the 

same section. 

Gilmore, C. W., Vertebrate faunas of the Ojo Alamo, Kirtland, and 

Fruitland formations: U. S. Geol. Survey Prof. Paper 98, p. 288, 1916. 

2 Cope, E. D., The relations of the Puerco and Laramie deposits: 

Am. Naturalist, vol. 19, p. 986, 1885. 
68 REPTILIAN FAUNAS OF SAN JUAN COUNTY, N. MEX. 

Crocodile remains are also found in the Ojo 

Alamo, Kirtland, and Fruitland formations,' 

but no new materials were obtained by the 

expedition of 1916. 

Class PISCES. 

Genus LEPISOSTEUS Lacepede, 18Q3. 

Lepisosteus sp. 

In recent years it has become customary for 

paleontologists to refer all fossil fish scales to 

Lepisosteus, a genus founded on living specimens. This procedure has but little significance outside of indicating the ganoid nature 

of the scales. That more than one genus is 

represented among the materials thus referred 

I Gilmore, C. W., Vertebrate faunas of the Ojo Alamo, Kirtland, and 

Fruitland formations: U.S. Geol. Survey Prof. Paper 98, p. 289,1916. 

is quite probable, but more perfect specimens 

are needed before this matter can be decided. 

It is quite impossible to identify genera or 

even species from these simple lozenge-shaped 

scales. 

The present collection contains ganoid scales 

from the Kirtland and Puerco formations 

which were found 8 miles N. 70° E. of Kimbetoh, in sec. 21, T. 23 N., R. 8 W., 820 feet 

above the base of the Puerco, in the Torrejon; 

8 miles N. 60° E. of Kimbetoh, in sec. 17, T. 

23 N., R. 8 W., 840 feet above the base of the 

Puerco in the Torrejon; and 21 miles south of 

west of Kimbetoh, in sec. 3, T. 22 N., R. 10 W., 

200 feet above the base of the Kirtland.2 

2 Other Upper Cretaceous localities are listed in U. S. Geol. Survey 

Prof. Paper 98, p. 302,1916. 
PLATES. 


U. PROFESSIONAL PAPER 119 PLATE I S. GEOLOGICAL SURVEY 

1 2 


COMPSEMYS PARVA HAY. 


No. 8528, U. S. N. M. 1, Carapace; 2, plastron. Natural size, See p. 13. 
PROFESSIONAL PAPER 119 PLATE II 

V. S. GEOLOGICAL SURVEY 

2
 1 
 COMPSEMYS VAFER HAY. 

No. 8529, U. S. N. M. 1, Carapace; 2, plastron. Three-fourths natural size. See p. 16. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE III 

1 
 2
 COMPSEMYS PUERCENSIS GILMORE, N. SP. 

Type; No. 8544, U. S. N. M. 1, Carapace; 2, plastron. Three-fourths natural size. See p. 19. 
U. S. GEOLOGICAL, SURVEY PROFESSIONAL PAPER 119 PLATE IV 

1 


COMPSEMYS TORREJONENSIS GILMORE, N. SP. 

Type; No. 8549, U. S. N. M. 1, Carapace; 2, plastron. One-half natural size. See p. 21. 
PROFESSIONAL PAPER 119 PLATE V 

U. S. GEOLOGICAL SURVEY 

ADOCUS KIRTLANDIUS GILMORE, N. SP. 


Type; No. 8593, U. S. N. M. Carapace. One-half natural size. See p. 26. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE VI 


ADOCUS KIRTLANDIUS GILMORE, N. SP. 


Type; No. 8593, U. S. N. M. Plastron. One-half natural size. See p. 28. 

PROFESSIONAL PAPER 119 PLATE VII 

U. 8. GEOLOGICAL SURVEY 

2 


1 ADOCUS BOSSI GILMORE, N. SP. 


Type; No. 8613, U. S. N. M. 1, Carapace, one-fourth natural size; 2, plastron, about three-eighths natural size. See p. 29. 

U. S. GEOLOGICAL SURVEY 

PROFESSIONAL PAPER 119 PLATE VIII 


ADOCUS BOSSI GILMORE, N. SP. 


No. 8577, U. S. N. M. Plastral view. One-half natural size. See p. 32. 

PROFESSIONAL PAPER 119 PLATE IX U. S. GEOLOGICAL SURVEY 

ADOCUS HESPERIUS GILMORE, N. SP. 


Type; No. 8596, U. S. N. M. Carapace. One-half natural size. See p. 33. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE X

2 

1 

ADOCUS ONEROSUS GILMORE, N. SP. 

Type; No. 8594, U. S, N. M. 1, Carapace; 2, plastron, One-fourth natural size. See p. 35, 
PROFESSIONAL PAPER 119 PLATE XI 

U. S. GEOLOGICAL SURVEY 

2 

ADOCUS ANNEXUS (HAY). 


No. 8606, U. S. N. M. 1, Carapace; 2, plastron. One-fourth natural size. See p. 37. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XII 


ADOCUS ANNEXUS (HAY). 


Type; No. 6539, U. S. N. M. Plastron. One-half natural size. See p. 39. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XIII 


HOPLOCHELYS CRASSA (COPE). 


No. 8525, U. S. N. M. Carapace. About natural size. See p. 41. 

U. S. GEOLOGICAL SURVEY 

PROFESSIONAL PAPER 119 PLATE XIV 

2 HOPLOCHELYS BICARINATA HAY. 

No. 8524, U. S. N. M. 1, Carapace; 2, plastron. One-half natural size. See p. 43. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XV

1 2 
 HOPLOCHELYS LAQUEATA GILMORE, N. SP. 


Type; No. 8527, U. S. N. M. 1, Carapace; 2, plastron. One-half natural size. See p. 47. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XVI 


1 
 2
 HOPLOCHELYS ELONGATA GILMORE, N. SP. 


Type; No. 8553, U. S. N. M. 1, Carapace; 2, plastron. One-half natural size. See p. 50. 

U. PROFESSIONAL PAPER 119 PLATE XVII S. GEOLOGICAL SURVEY 

PLASTOMENUS ROBUSTUS GILMORE, N. SP. 


Type; No. 8538, U. S. N. M. Carapace. Seven-sixteenths natural size. See p. 53. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XVIII 

1. PLASTOMENUS ROBUSTUS GILMORE, N. SP. 


Type; No. 8538, U. S. N. M. Right half of plastron. One-half natural size. See p. 54. 


2. ASPIDERETES VEGETUS GILMORE, N. SP. 


Type; No. 8539, U. S. N. M. Plastral bones. Three-fourths natural size. See p. 58. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XIX 

1. ASPIDERETES PERPLEXUS GILMORE, N. SP. 


Type; No. 8532, U. S. N. M. Carapace. About one-half natural size. See p. 60. 


2. PLASTOMENUS TORREJONENSIS GILMORE, N. SP. 3. COMPSEMYS PARVA? HAY 


Type; No. 8543, U. S. N. M. Carapace. Natural size. Seep. 55. No. 8598, U. S. N. M. Plastron. Natural size. See p. 16. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XX 


ASPIDERETES REESIDEI GILMORE, N. SP. 


Type; No. 8537, U. S. N. M. Carapace. About three-fourths natural size. See p. 56. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XXI 


ASPIDERETES VEGETUS GILMORE, N. SP. 


Type; No. 8539, U. S. N. M. Carapace. Three-fourths natural size. See p. 57. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XXII 


ASPIDERETES QUADRATUS GILMORE, N. SP. 


Type; No. 8545, U. S. N. M. Carapace. One-half natural size. See p. 59. 

PROFESSIONAL PAPER 119 PLATE XXIII U. S. GEOLOGICAL SURVEY 

1. ASPIDERETES SAGATUS HAY. 


No. 8554, U. S. N. M. Right half of plastron. Natural size. See p. 62. 


2. UNIDENTIFIED SPECIES OF PLASTOMENUS. 


No. 8553, U. S. N. M. Plastral hones. Natural size. 1. hyo., Left hyoplastron; 1. hypo., left hypoplastron. See p. 53. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XXIV 


AMYDA ELOISAE GILMORE, N. SP. 


Type; No. 8540, U. S. N. M. Carapace. About three-fourths natural size. See p. 63. 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XXV 

1 2 


MEDIAN PORTION OF THE FRILL OF A CERATOPSIAN DINOSAUR, PROBABLY PERTAINING TO THE GENUS 

CERATOPS. 

No. 8604, U. S. N. M. 1, Dorsal view. a, anterior end; p, posterior end. 2, Ventral view. a, anterior end; p, posterior end. One-half natural 

size. Seep. 64. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 119 PLATE XXVI 

1. STEGOPELTA LANDERENSIS WILLISTON. 


Type. Dorsal surface of left ilium. One-fourth natural size. After Moodie. See p. 67. 


2: UNIDENTIFIED MEMBER OF THE SCELIDOSAURIDAE FROM OJO ALAMO FORMATION. 


No. 8571, U. S. N. M. Left scapula. A, Acromion process; G, glenoid cavity. About one-half natural size. See p. 65. 

INDEX. 

Names in italic are synonyms. 

Acknowledgments for aid 

Adocus Cope, geologic distribution of 

history and distinguishing characters of 

key to 

annexus (Hay) Gilmore 

bossi Gilmore, n. sp 

hesperius Gilmore, n. sp 

kirtlandius Gilmore, n. sp 

onerosus Gilmore, n. sp 

Alamosemys annexa Hay. 

Amyda Oken, species added to 

eloisae Gilmore, n. sp 

Aspideretes Hay, new species assigned to 

perplexus Gilmore, n. sp 

quadratus Gilmore, n. sp 

reesidei Gilmore, n. sp 

sagatus Hay 

vegetus Gilmore, n. sp 

Baena nodosa Gilmore 

sp. undet 

Baenidae Cope, genus representing 

Boss, N. H., acknowledgment to 

Brown, Barnum, cited 

Ceratops sp 

Ceratopsian specimen 

Chelydra crassa Cope 

Clark, F. R., collection of specimens by 

Collection of specimens 

Compsemys Leidy, distinguishing characters of 

geologic distribution of 


parva Hay 


puercensis Gilmore, n. sp 


torrejonenAis Gilmore, n. sp 


vafer 


Crocodilia, specimens representing 

Dermatemydidae, species representing 

Dermatemys sp. Cope. 

Dinosauria, fpecimens representing 

Page. 


7 


26 


25-26 


26 


37-40, Pls. XI, XII 


29-33, Pls. VII, VIII 


33-35, Pl. IX 


26-29, Pls. V, VI 


35-37, Pl. X 


37 


62 


63-64, P1. XXIV 


56 


60-61, Pl. XIX 


59-60, Pl. XXII 


56-57, Pl. XX 


61-62, Pl. XXIII 


57-59, Pls. XVIII, XXI 


24 


24-25 


24 


7 


65 


64-65, P1. XXV 


65 


41 


7 


7 


12-13 


13 


13-16, Pls. I, XIX 


19-21, Pl. m 


21-24, Pl. IV 


16-19, Pl, II 


67-68 


25 


41 


64 


Page. 

Fruitland formation, fauna of 7,8 

Goldberg, Louis, acknowledgment to 

Hadrosauridae Cope, use of name 64 


Hadrosaurinae Lambe, specimen representing 64 


Hay, 0 P, acknowledgment to 7 


cited 39,41,46 


Hoplochelys Hay, distinguishing characters of 40 


geologic distribution of 41 


bicarinata Hay 43-47, Pl. XIV 


crassa (Cope) Hay 41-43, Pl. XIII 


elongata Gilmore, n. sp 50-52, Pl. XVI 


laqueata Gilmore, n. sp 47-49, Pl. XV 


saliens Hay 49-50 


Kirtland formation, fauna of.. 7,8 

Lepisosteus sp., specimens representing 68 


Matthew, W. D., acknowledgment to 7 


Megalosauridae, specimen representing 67 


Neurankylus baueri Gilmore 11-12 


Ojo Alamo formation, fauna of . 7,8-9 

Plastomenus Cope, specimens representing 52-53 


robustus Gilmore, n. sp 53-54, Pls. XVII, XVIII 


torrejonensis Gilmore, n. sp 55-56, Pl. XIX 


Pleurosternidae Cope, genera included in 11 


Puerco formation, fauna of 7-8,9-10 


Reeside, J. B., jr., collection of specimens by 7 


Saurlophinae Brown, specimen representing 64 


Scelidosauridae Huxley, specimens representing 65-67, Pl. XXVI 


Specific characters, synopses of 11 


Specimens, list of 10 


Sumichrast, cited 40 


Torrejon formation, fauna of 7-8,9,10 

71