Page:The Eurypterida of New York Volume 1.pdf/21

 the chapters on the phylogeny and taxonomic position of the eurypterids. Holm had for the subject of his investigations the same  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   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  Hall (which he preferred to call  ) from the Catskill beds and in the next year the same author announced the discovery of a true eurypterid  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