# The Eurypterida of New York/Volume 1/History of investigations

INTRODUCTION HISTORY OF INVESTIGATIONS UPON THE EURYPTERIDS OF NEW YORK AND ADJOINING TERRITORY
The Siluric rocks of New York are, of all countries of the world, the richest in eurypterids. The first example ever described was obtained here. The specimen was found in Westmoreland, Oneida co., and was regarded by Dr S. L. Mitchill [1818] Figure 1 DeKay's figure of Eurypterus remipes as a fossil fish of the genus Silurus, an error obviously induced by the peculiar catfishlike aspect of the carapace. In 1825, James E. DeKay, afterward the distinguished zoologist of the Natural History Survey, recognized the arthropod nature of this fossil. He erected for it the genus eurypterus, and termed the species E. remipes, considering it as a crustacean of the order Branchiopoda, naming Apus, among others, as a recent form probably of near relation to it and suggesting that Eurypterus may be a connecting link between the trilobites and recent Branchiopoda.
In 1835, Dr Richard Harlan described the Eurypterus lacustris, the predominant species in the Siluric waterlime at Buffalo, and next in abundance to E. remipes.
These descriptions preceded those of European species by a considerable interval; hence they were frequently copied into early ​textbooks and the Baltic species now known as E. fischeri long passed current as E. remipes.
From 1835 until 1858-59, little was added to our knowledge of the eurypterids except through brief descriptions of a few fragmentary remains from the rocks of Scotland and Russia; then almost simultaneously three fundamental publications appeared, representing the three areas that still today furnish the principal eurypterid faunas. These were Nieszkowski's De Euryptero Remipede [1858], describing elaborately the Baltic species now known as E. fischeri; Huxley and Salter's classic monograph On the Genus Pterygotus; and James Hall's exhaustive description and beautiful illustration of the eurypterid fauna of the waterlimes of New York, in volume 3, of the Palaeontology of New York [1859]. Nieszkowski's and Hall's papers supplement each other very fully; both described for the first time the whole organization of a eurypterid; they recognized the full number and character of the cephalothoracic appendages exclusive of the chelicerae whose existence was even at this early date intimated by Hall [op. cit. p. 396, footnote]; they established the number of preabdominal and postabdominal segments. They failed, however, in making out the correct number of sternites, Hall recognizing but one (the operculum) and considering the others as ringlike segments, while Nieszkowski (under the guidance of Dr Fr. Schmidt) found out the true platelike character of the sternites, but assumed their number to be six. Huxley and Salter at the same time restored with approximate accuracy the organization of Pterygotus. Both Nieszkowski and Hall recognized the close relationship of the eurypterids with Limulus, while Huxley and Salter adduced other crustaceans for comparison.
Hall described the appendages of the cephalothorax and that of the female operculum in great detail and with his usual accuracy. He ​added to the longer known species of eurypterids (E. remipes and E. lacustris) the following new types, all from the rocks of New York:
| Eurypterus microphthalmus | E. pachychirus |
| E. lacustris var. robustus | E. pustulosus |
| E. dekayi |
He erected the new subgenus Dolichopterus (now given full generic standing), for the species D. macrochirus and also recorded the presence of the genus Pterygotus (theretofore known only from Scotland) in the Salina waterlime, describing three species, viz, P. cobbi, P. macrophthalmus and P. osborni.
It is obvious that Hall, with his accustomed thoroughness, had availed himself of all New York collections extant, from the fact that for a decade and a half not a line was added to his investigations on American species, notwithstanding the intense activity in other branches of paleontology, and the further fact that Henry Woodward was meanwhile [1866-78] publishing his excellent Monograph of the British Crustacea of the Order Merostomata. During this period the large cement quarries at Buffalo were gradually producing a great number of striking specimens and these became somewhat widespread through the museums until, in later years and with keen and intelligent interest the proprietor of the quarry took measures to see that they were carefully safeguarded and donated to the Museum of the Buffalo Society of Natural Sciences. Some of the early collectors in Buffalo undertook to describe the supposed new material that at first found its way into that museum but, being trained in branches of science remote from paleontology, they succeeded only in creating for the most part a burdensome mass of synonyms. Thus Grote and Pitt [1875–78] described the following:
Eusarcus scorpionis, representing a new and important genus E. grandis (=E. scorpionis) Pterygotus cummingsi (not properly defined) ​Pohlman [1881, 1882, 1886] published descriptions of the following eurypterids from these rocks at Buffalo:
Pterygotus buffaloensis Ceratiocaris grandis (=Pterygotus grandis (Pohlman) C. & R.) Eurypterus giganteus (=E. pustulosus Hall) Pterygotus globicaudatus (=E. pustulosus Hall) P. acuticaudatus (=P. buffaloensis) P. quadraticaudatus (=P. buffaloensis) P. bilobus Huxley & Salter (=P. buffaloensis) Eurypterus scorpionis Grote & Pitt (=Dolichopterus macrochirus Hall)
While the splendid collection at Buffalo was being brought together and some part of its treasures made known by the publications referred to, other rocks of this State as well as of adjoining regions were giving evidence of the presence of very remarkable eurypterid remains.
In 1882 Whitfield recorded the occurrence of an Eurypterus in the Siluric waterlime of Ohio, which was fully described as E. eriensis in the Report of the Geological Survey of Ohio, volume 7, 1893, and Walcott announced the discovery of a multispinose eurypterid leg in the Utica slate near Holland Patent, Oneida co., N. Y. The genus Echinognathus was proposed for this new type and the species described as E. clevelandi.
In the same year Prof. D. S. Martin at a meeting of the New York Academy of Sciences reported that he had seen in the State Museum a head shield nearly a foot in length and breadth from the Catskill beds at Andes in Delaware co., N. Y. This was described and figured by Hall the following year as Stylonurus excelsior, a gigantic representative of a genus already known from the Ludlow beds of Scotland. Another carapace of this species from the Catskill beds of Pennsylvania was described the same year by Claypole as Dolichocephala lacoana.
The next year [1884] James Hall described for the Second Geological Survey of Pennsylvania an interesting fauna of eurypterids found in the Productive Coal Measures. The first announcement of a eurypterid of ​Carbonic age from the American continent had been made in 1868 by Meek and Worthen who described Eurypterus mazonensis from the Coal Measures of Illinois, erecting for it the subgenus Anthraconectes, and in 1877 C. E. Hall described two species (E. pennsylvanicus and E. mansfieldi) from the Coal Measures of Pennsylvania. James Hall noted four species from the Carbonic of that State, adding two types to those before known, and he described besides a new form from the Chemung group of Warren, Pa. (E. beecheri) which Beecher later determined to be a Stylonurus.
Considerable progress in the understanding of the organization of the eurypterids and especially of the genera Eurypterus and Pterygotus, was made by Fr. Schmidt's admirable investigations entitled Die Crustaceenfauna der Eurypterenschichten von Rootziküll auf Oesel published in 1883. Nieszkowski's work had already been done under Dr Schmidt's supervision and Schmidt now carried out a very detailed examination of the remains of Eurypterus fischeri and Pterygotus osiliensis. He was thereby enabled to correct many details of Hall's and Nieszkowski's descriptions of the appendages; to show the existence of five "Blattfüsse" or sternites open on the ventral side, as in Limulus; to recognize sexual differences in the opercular appendages; to establish the correct number of walking legs in Pterygotus (8, while Woodward assumed 6), and the form and position of the epistoma.
In 1884 Whiteaves made known an Eurypterus (E. boylei) from the Guelph limestone of Canada, and in 1888 Matthew described as Eurypterella ornata, a peculiar Devonic organism that is referred by him to this group.
In this year, 1888, also appeared volume 7 of the Palaeontology of New York by Hall and Clarke. This volume supplements the description of the Siluric eurypterids in volume 3, by bringing together the remaining merostomes from the State of New York and the adjoining regions. It contains a full size drawing of Hall's type of the famous carapace of Stylonurus excelsior and gives an ​account of the chelicera and first endognathite, as well as the coxae of other legs of this Stylonurus, which were discovered and worked out by the junior author of that volume from the underside of the fragmentary carapace that served for Claypole's description of the species. There was further described a species of Eurypterus (E. prominens) from the Clinton beds of New York, one from the Waverly beds near the boundary of Pennsylvania and New York (E. approximatus); and a tubular body from the Portage beds of Yates county, which Dawson had described as Equisetides wrightianus, and Jones & Woodward regarded as probably a phyllocarid (Echinocaris), was provisionally referred to Stylonurus.
Two years later (1890) Claypole announced the occurrence of eurypterids in the waterlime of Kokomo, Indiana, and he described therefrom a large Eusarcus, for which he first proposed the generic name Eurysoma and later Carcinosoma. A species of Eurypterus from the same locality was described in 1896 by Miller and Gurley.
While thus in the last decades of the preceding century on this side of the Atlantic, the fragments of the eurypterids scattered in the formations of New York, Ohio and Illinois were brought together and published, important work on the organization of the eurypterids was done in Europe. We refer here to Laurie's paper on the Anatomy and Relations of the Eurypterida [1893] and to Holm's new investigation of Eurypterus fischeri [1896]. Laurie had already added considerably to our knowledge of the Scottish species by descriptions of new forms from the Pentland Hills [1892], among them the new genera Drepanopterus and Bembycosoma, and had discovered the epicoxite and gillplates in Slimonia; he now took up the discussion of the anatomy of the genera Slimonia, Pterygotus, Eurypterus and Stylonurus, the relations of the eurypterids among themselves, to the trilobites and crustaceans, to Limulus, the scorpion and other arachnids. We have given full appreciation of this work in ​the chapters on the phylogeny and taxonomic position of the eurypterids. Holm had for the subject of his investigations the same Eurypterus fischeri from Oesel that had already been studied by Nieszkowski and Schmidt, and he succeeded by most clever manipulation in isolating the chitinous test of the animal which at Oesel is not metamorphosed into a carbonaceous film as in other localities, and was able to elaborate its organization in such detail that E. fischeri has really become the most completely known of all extinct animals, and our exact knowledge of it is quite comparable with that of its recent relatives. By comparison with Limulus the differences in the appendages of the first and second sternites were referred to their proper sexes. Many details of structure were discovered, such as the minute chelicerae, the epicoxite of certain coxal segments, the endostoma of the posterior margin of the mouth, the connection of the metastoma with the gnathobase, the clasping organ of the second endognathite of the male, the originally composite nature of the metastoma, corresponding to the chilaria of Limulus and the interior tubular processes of the female opercular appendage. This work served to bring out with still greater force the numerous homologies and consequent close relationship of the eurypterids to Limulus.
A comprehensive review of the more important of these discoveries with the status of the classification of the merostomes, was given in 1900 by Clarke in the chapter Eurypterida, Eastman's English edition of Zittel's Textbook of Palaeontology, where note was also taken of the ontogeny of Eurypterus.
In 1900 also there appeared C. E. Beecher's reconstruction of the giant Stylonurus excelsior Hall (which he preferred to call S. lacoanus) from the Catskill beds and in the next year the same author announced the discovery of a true eurypterid (Strabops thacheri) from the Cambric of Missouri, the only eurypterid from that fauna thus far known.
At this date, aside from the few scattered individuals discovered in the Clinton and Manlius (Siluric), Portage and Catskill (Devonic) beds ​there was only one large and typical eurypterid fauna, that of the Bertie waterlime, known from the rocks of this State, and except the small fauna of the waterlime of Kokomo, from the entire continent. Of so much greater interest therefore is the discovery within a few years of three new and larger faunas. The first is that of the Pittsford shale at the base of the Salina beds in Monroe county, found by Clifton Sarle. Its most striking and common member is the representative of a new genus, termed by its discoverer Hughmilleria. This is a form which has a very interesting bearing on the phylogeny of Pterygotus and Slimonia. The eurypterid portion of the remarkable arthropod fauna of Pittsford has been elaborately described and figured by Mr Sarle in the Report of the State Paleontologist for 1902. It consists of the following species:
| Hughmilleria socialis | Pterygotus monroensis |
| H. socialis var. robusta | Stylonurus (multispinosus C. & R.) |
| Eurypterus pittsfordensis |
The associated forms (crustacean species of Ceratiocaris, Pseudoniscus, Emmelezoe, Bunodes, mostly described by Clarke), the peculiar lithologic surroundings of this fauna, and the fact that through this discovery the salt and gypsum-bearing Salina beds are now known to be both underlain and overlain by Eurypterus beds, all bear on the problem of the physical conditions under which these animals lived.
A second discovery was made in 1906 by the junior author of this book in the shales of the Shawangunk grit formation of southeastern New York. A preliminary description of this fauna was published by the senior author in 1907 [N. Y. State Mus. Bul. 107]. It consists of one species of Eurypterus, one of Eusarcus, one of Dolichopterus, six of Stylonurus, one of Hughmilleria and one of Pterygotus. It has furnished a contribution to the organization of the eurypterids in a specimen of Stylonurus, retaining all four posterior legs of one side, in the light of which previous restorations of that genus are greatly modified. The most novel feature of the Shawangunk grit fauna, is the presence of larval stages of ​Eurypterus, Hughmilleria, Stylonurus and Pterygotus from the nepionic, almost microscopic, stage onward. These ontogenetic stages have been carefully described in the present work and their bearing on the much discussed relationship of the eurypterids to Limulus and the scorpions estimated.
The third fauna is, as already noted in the preface, a discovery of quite recent date made by the junior author in 1910 in the Frankfort shale (Upper Lower Siluric) along its outcrops in the counties of Schenectady and Schoharie. This material is not very well preserved and owing to its incomplete character we are for the present forced to form our conception of specific values from the carapaces alone and to unite with them such other parts of the test as are presumably referable to them. For this reason too, the generic references must be regarded as open to question and of provisional value only, there always being the presumption that when the full anatomy of these Lower Siluric creatures becomes really known they will prove to be genetically unlike the species of later date. While the morphology of these species is not yet wholly clear, the age of the fauna is a factor of chief interest, for the Lower Siluric has hitherto afforded only a few fragments known under the names Echinognathus clevelandi and Megalograptus welchi. With our present knowledge of this assemblage we are entitled to the inference that in a late stage of the Lower Siluric the eurypterids had attained a diversity and an abundance quite as great as in the Upper Siluric. We estimate this diversity in some measure on the striking differences in test sculpture presented and even though this may be an unsafe guide to either specific or generic distinctions yet these sculptures are in so large measure unlike those of better known species that they must be given full worth. These characters are fully elucidated at the proper place in the descriptive part of this book and there are among them undeniable evidences of ornament which we have come to recognize as indicative of the genera Eurypterus, Eusarcus, Hughmilleria and Pterygotus. Hence these and other outstanding terms have been adopted in the ​characterization of the assemblage, which consists as far as now known of the following species:
| Eurypterus? (Dolichopterus?) stellatus | D. latifrons |
| E. pristinus | Hughmilleria magna |
| E. megalops | Pterygotus nasutus |
| Eusarcus triangulatus | P. prolificus |
| E. longiceps | Stylonurus? limbatus |
| Dolichopterus frankfortensis |
* ↑ Hall submitted his collection to Professor Agassiz who gave "his opinion most unequivocally that the Eurypteri are closely related to Limulus, belonging even to the same order."
* ↑ The arachnidan affinities of Limulus had been for some time the subject of discussion among zoologists, especially in Lankester's paper: Limulus an Arachnid? [1881].