THE EXTINCT CHELOXIAXS. 



261 



Dr. Gray to belong to a group now represented in Yucatan Dermatoclemys. In the Wealden there 

 are the remains of a Marine Turtle ; and the true marine forms, Chelone camperi, C. benstedi, and 

 C. pulchriceps, and a Protemys are from the Cretaceous series. The number of Turtles in the London 

 Clay is great, and the skull of Chelone gigas measures a foot across. One resembles a Trionyx in the 

 shape of its snout, but its carapace and plastron are well ossified, and it is called C/telone longiceps. The 

 Eocene of Hordwell yielded a " Soft Turtle;" this Trionyx is accompanied by eight fossil Emydes. The 

 order is represented in the Miocene and Pliocene of Europe, and in the Tertiaries of America, and the 

 gigantic sub-Himalayan ColossocJielys atlas is accompanied by the recent Emys tecta (Gray). Finally, 

 the island of Malta has yielded gigantic Tortoise remains, which are allied to the recent and extinct series 

 of the Mascai-enes and of the Galapagos Islands. Descriptions of the fossil Chelonians of the United 

 States are to be found in the magnificent work of Cope on the " Vertebrata of the Cretaceous Forma- 

 tions of the West," a book given to most European naturalists by the wise generosity of the Senate, 

 and Dr. Hayden, head of the Geological Survey. The Tertiary strata have yielded fossil Trionycides and 

 species of Emys allied to modern American kinds; and Cope discovered in the chalk of Kansas a huge 

 Turtle with nippers considerably over fifteen feet in length, and this Protostega had the bony characters 

 of a youthful modern form. It is allied to Sphargis. Equally interesting is the genus Plastomenas 

 of Cope, which embraces the anatomical characters of Trionyx and Emys, and which is found at the 

 top of the Cretaceous and in the Eocene. Trionyx has been found in the Green Sand of New Jersey, and 

 Leidy has described one from the celebrated Bad Lands of Montana. A form with a long tail like 

 Chelydra, and as long as Temminck's Snapper, has been described by Cope, and was found with his 

 great Turtle. As yet no Land Tortoises have been discovered fossil in America. 



The European Emys has been found in England in a sub-fossil condition. 



Giinther states that the Mascarene great Tortoises Testudo triserrata, T. inepta, and two others 

 are extinct, and that there is Testudo vosmceri extinct in the island of Rodriguez. Testudo ephippium 

 of the Galapagos Archipalago is also one of these lately extinct forms. 



CLASSIFICATION OF THE ORDER OHELONIA AND OF THE PRINCIPAL GENERA. 



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