On some Bivalve Entomostraca, chiefly Cypridinidæ, of the Carboniferous Formations
Authors: Jones T. Rupert 
Published: October 2009

Abstract

Bivalved Entomostraca are abundant in many shales and limestones throughout the Carboniferous formations; in the lists published in the ‘Transactions of the Geological Society of Glasgow’ (vol. ii. 1867, and vol. iii. suppl. 1871) upwards of 50 species are enumerated as known in the coal-fields of Western Scotland alone. Other species have since been recognized in that and other localities. Some of the larger forms of Ostracoda are not rare in the Carboniferous Limestone of Belgium and the British Islands; and, indeed, in some instances they are so plentiful as to constitute masses or bands of limestone, as at Longnor (Derbyshire), Bolland (Yorkshire), Bathgate (Scotland), Poolvash (Isle of Man), Caldy Island (South Wales), Kildare (Ireland), &c. Here and there in the Coal-shales some large forms, especially
Cypridinæ
, also occur.

Many years ago some of these larger Ostracods were figured and described by Professors J. Phillips (1836), M'Coy (1839), and De Koninck (1841), and their Entomostracal relationship pointed out. The collections made by M. J. Bosquet, F.C.G.S., in Belgium, Mr. Joseph Wright, F.G.S., at Cork, Ireland, Mr. J. H. Burrow, M.A., at Settle, Yorkshire, Mr. Young, Glasgow, Mr. Grossart, Salsburgh, Dr. Rankin, Carluke, and others, and submitted to the author and his friend Mr. J. W. Kirkby, have elucidated many obscure points in the history of these old Entomostraca. Numerous other specimens from Ireland, Scotland, Yorkshire, Derbyshire, and the Isle of Man, communicated by friends, have also been studied; and the results will be given in detail in a Monograph by Messrs. Jones and Kirkby, to be published by the Palæontographical Society, and now in the press. The main points of geological interest arrived at are as follows:-

The
Entomoconchus
of M'Coy proves to have the Cypridinal character of anterior sinus and gape, as intimated by Messrs. Jones and Kirkby in 1863 (‘ Rept. Brit. Assoc.’ for 1863, Tr. Sect. p. 80); and besides
E. Scouleri
, M'Coy, which is found in Belgium, Yorkshire, and Ireland, together with a variety
ovalis
(Ireland), two other species have now been determined,
E. orbicularis
(Cork, Ireland) and
E. globosus
(Beith, Scotland), thanks to the researches of Mr. Joseph Wright, F.G.S., of Belfast, and Mr. John Young, of Glasgow, respectively, all from the Mountain Limestone.

A closely allied genus
Offa
* is also indicated, in which the sinus and gape are very slightly pronounced, in a carapace otherwise somewhat resembling the foregoing. Only one species,
O.Barrandiana
(Cork, Ireland), is as yet known.

M'Coy's “
Daphnia primæva
” belongs to
Cypridina
proper, judging from the carapace; and besides the Irish specimen, a group of three hundred, found by Dr. Rankin and Mr. John Young in a coprolite from the Lower Limestone Shale, near Carluke, are the only known examples, except some doubtful specimens in the Poolvash limestone of the Isle of Man, and a cast in the Permian limestone of Sunderland. There are several other Carboniferous species of
Cypridina
.
C. radiata
has been found abundantly in the Coal-measure shales of Glasgow by Mr. John Young, and in the Coal-measures of North Staffordshire by Mr. Molyneux, F.G.S. Its carapace-valves possess a curious and characteristic stellate structure.
C. Wrightiana
and
C.Bradyana
are in Mr. J. Wright's collection from the Carboniferous Limestone of Cork.
C. brevimentum
is one of the most abundant of Carboniferous
Cypridinæ
it is somewhat oval, like
C.primæva
, but has a much greater notch and sinus, and is rather variable in outline. It occurs in the Mountain Limestone of Belgium, Derbyshire, and Ireland, and probably in that of Caldy Island and the Isle of Man.

C. scoriacea
,
C. Grossartiana
,
C. Thomsoniana
,
C. Hunteriana
, and
C. Phillipsiana
are from the Lower Carboniferous strata of West Scotland; the last is not rare, and occurs at Cork also.
C. Truniformis
is both Irish and Belgian, from the same geological horizon as the foregoing.
C. oblonga
is from the Cork limestone.

The foregoing
Cypridinæ
have oval-oblong valves notched anteriorly; an allied group from the Mountain Limestone have ovate valves, more or less deeply notched in front, for which, having no recent analogues, we institute a new genus
Cypridinella
. These are common in the Mountain Limestone, and present seven species:-
Cypridinella Cummingii
from the Isle of Man;
C. superciliosa
from Cork (Ireland), Settle (Yorkshire), and Bathgate (Linlithgowshire);
C. clausa
from Cork;
C. Bosqueti
, Visé, Belgium;
C. Maccoyiana
and
C. vomer
, Cork; and
C. monitor
, Settle and Visé The last is typical of the peculiarly produced carapace, with antero-ventral prow beneath the retiring sinus, a form which reminds one of the profile of such iron-clad naval “rams“ as the “Monitor“ and “Merrimac.”

Carapace-valves like those of
Cypridina
, but impressed with a transverse dorsal or nuchal furrow, characterize the new genus
Cypridinella
, leading us towards the
Cypridella
of De Koninek (restricted); and equally abundant with the foregoing in the Mountain Limestone we have:—(1)
Cypridinella clausa
, Cork; (2)
C. Burrovii
, abundant at Settle, and its variety
longnoriensis
, locally plentiful at Longnor, in Derbyshire; (3)
C. intermedia
, Bathgate; (4)
C. elongata
abundant at Visé and its variety
hibernica
plentiful at Cork; (5)
C. galea
, Cork; (6)
C. vomer
, and varr.
cultrata
and
uncinata
, Cork; (7)
C. alta
, Cork and Visé; (8)
C. Bosqueti
, Visé.

An additional feature, namely a subcentral tubercle, is the basis for another generic division of the numerous Cypridinoid carapaces of the Mountain Limestone; and amongst this group we have:-(1)
CYPRI- DELLA
Edwardsiana
(
Cypridina
, De Koninck, 1841), which has the general shape of
Cypridinella
and
Cypridellina
, but with a very small notch; it has, with the aforesaid tubercle, subsidiary smaller tubercles; the larger tubercle on each valve in this species appears to be truncate, and possibly the base of a spine.
C. Edwardsiana
occurs in the Belgian limestone, and is represented at Beith (Ayrshire), Bathgate (Linlithgowshire), and Cork (Ireland) by thee variety
septentrionalis
. (2)
C.Koninckiana
has the subcentral tubercle only, with a deep nuchal furrow, apiculate end, and strongly hooked front. It is common at Cork. (3)
C. obsoleta
, from Cork, has tubercle and furrow both faint. (4)
C. Wrightii
, from Cork, approaches
C. cruciata
, De Kon., in shape, but is easily distinguished. (5)
C. quadrata
, from Visé is longer and squarer than
C. cruciata
, which has not been met with in the British area. (6)
C. cyprelloides
, from Cork, approaches the genus
Cyprella
either as a link or an isomorph.

Sulcuna
is a new genus intended to comprise two forms in which the valves are indented with the anterior sinus and notch, and have the general outline of
Cypridella Wrlghtii
; but the dorsal edge is so deeply incised by the nuchal furrow as to have its anterior moiety raised into a slanting hump, orprocess pointing backwards and outwards.
S. lepus
and
S. cuniculus
are the two proposed species, both from the Carboniferous Limestone of Cork.

Cyprella
, De Koninck (restricted) has an oval or ovate carapace,notched as in
Cypridina
and allied genera; but the surface is transversely striated with parallel furrows or slight step-like markings, associated with a minute reticulate ornament. (1)
C. chrysalidea
, De Koninck, is long, oval, and somewhat pupa-like; it occurs at Settle, as well as in Belgium; but its variety
subannulata
, representing it at Cork, is found at Settle also; and either the type or tile variety occurs in the Isle of Man, Derbyshire, and Lintlithgowshire. (2)
C. annulata
(
Cypridina
, De Koninck, 1841), shorter and thicker than the foregoing, occurs in Belgium and at Cork, Settle, and Bathgate. All in the Mountain Limestone. The exact meaning of the details in Prof. De Koninck's figures of
Cypridella
and
Cyprella
appears evident on the study of the large series of specimens that have now been collated.

Returning to some forms more nearly related in the shape of the carapace to
Cypridina
, we find a very exact analogue of
BRADYCINETUS
(
B. Rankinianus
) in some carapaces discovered by Dr. Rankin in a small ironstone nodule from the Lower Carboniferous shales of Gare, near Carluke. To
PHILOMEDES
one form (
Ph.Bairdiana
) is doubtfully referable; it is from Cork. A modification of the Cypridinal carapace is seen in two species of the new genus
Rhombina
, which has a subcylindricaI carapace, with slanting ends, giving a rhomboidal shape to the valves, obliquely truncated at each end with parallel slopes. The antero-dorsal angle is the most prominent; and there is a slight notch beneath it.
Rh. hibernica
and
Rh, belgica
(from Cork and Visé respectively) differ in proportion and outline.

Polycope
is a recent Ostracodal genus of the Cladocopal group (
Cypridina
belonging to the
Myodocopa
), and has a suborbicular. carapace without a notch, with very slight, if any, indication of the sinus or place of the notch, and without any dorsal furrow. Such carapaces are not rare in some Lower Carboniferous strata. 1.
Polycope Burrovii
is subglobular, from Settle. 2.
P. simplex
, oval, obliquely truncated at the antero-ventral edge, is common at Cork and Duleek, Ireland; and Dr. Rankin found seventeen in one ironstone nodule from Braidwood, near Carluke. It is somewhat like
Cypridina primæva
; but the want of the notch and beak is its characteristic difference. 3.
P. Youngiana
, from the Lower Limestone of Campsie, near Glasgow, is oval and slightly pinched-in or indented on the antero-ventral quarter, and has a striolate ornament.

This genus is the last described in that portion of the Monograph which is now completed.
Cytherella
, belonging to an allied group, is known to occur in the Mountain Limestone; and
Leperditia
,
Beyrichia
,
Kirkbya
,
Moorea
, and
Entomis
, all palæozoic genera, abound; forms referable probably to
Cyther
,
Cypris
,
Candona
, &c. are also known in the Carboniferous formations.