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Show 1870.] DR. J E. GRAY ON THE DERMATEMYD.E. 713 scutes, and the under borders of the fifth, sixth, and seventh marginal scutes; these superadded scutes I propose to call 'submarginal scutes.' The Platysternon megacephalum, or large-headed Terrapin of the Chinese swamps, presents a corresponding but single supplementary ' submarginal scute' upon the under part ot each lateral production of the plastron." This statement about Platysternon is entirely erroneous; for that genus, as well as Dermatemys and Pleurosternon, has three small "submarginal scutes" between the abdominal and marginal plates (see Proceedings of the Zoological Society, 1831, p. 106, where the genus was originally described, and the ' Catalogue of Shield Reptiles,' p. 49). The Pleu-rosterna are found in the freshwater limestone of Purbeck; and Professor Owen divides them into four species. I am still inclined to retain the genus, and I think that probably, when we have more materials, we shall find that the fossil genus will form a distinct group of the family. Mr. Agassiz, in his ' Contributions to the Natural History of the United States,' published in 1857, probably misled by Dumerii's figure, observes:-"Emys berardi, Dum. et Bib., seems also to belong to this genus (Ptychemys), judging from the description and figure of the jaws published by A. Dumeril, ' Archives du Museum,' vol. vi. p. 251, t. 15" (vol. i. p. 434). The British Museum having received from Mr. Salvin a specimen of Dermatemys, which he obtained in Guatemala, I published in the ' Proceedings of the Zoological Society,' 1864, p. 125, a history of the genus and a description of the animal, which, unfortunately, was not in a very good state, as it had accidentally got dry through the evaporation of the spirit and had again been placed in spirit. In the ' Proceedings of the Academy of Natural Sciences' for 1868, p. 119, Mr. Cope describes a new species under the name of D. abnormis, from the Belize River, Yucatan, sent by Dr. Parsons, which differs in having the gular plates united and the vertebral plates broader than long. He observes that one species of Dermatemys, the D.mavei, is recognized by Dr. Gray as inhabiting Venezuela and Mexico. The same species, according*to the same author, has been subsequently named Emys berardii by Prof. Dumeril; and he further remarks, " I have not had an opportunity of seeing South- American specimens; but the excellent figure and descriptions of Gray render it certain that the individuals from that country, on which the species are based, really belong to another species from those of Mexico. The collection of the Smithsonian Institution furnishes another species from Belize, which I have hitherto identified as the same; the species may be thus distinguished." In a table he gives the characters by which he proposes to discriminate three species, D. abnormis, D. berardii, and D. mavei. I do not know why he described his second species under the name of D. berardii; for none of the characters which he gives to his species are to be found either mentioned in M . Dumerii's descriptions or shown in M . Dumerii's plate. I have no specimen possessing such characters as he gives to the species. |