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Show 712 DR. J. E. GRAY ON THE DERMATEMYD/E. [Nov. 1, The shell here described was presented to the British Museum by the Zoological Society, and is figured in the ' Catalogue of Shield Reptiles in the British Museum,' tab. 21. In the ' Catalogue of Tortoises in the British Museum,' and in the ' Catalogue of Shield Reptiles,' I formed a particular section in the family Emyda? for Platysternon and Dermatemys, because they had these additional plates on the sterno-costal suture. The group contains two families : the Dermatemydee are essentially water Tortoises, with broadly webbed feet; the Platysternidee are amphibious, and they have strong narrowly webbed toes and the front of the fore legs covered with large plates. M . Anguste Dumeril, in the ' Catalogue Methodique des Reptiles ' described, in 1851, a species under the name oi Emys berardii from two specimens in the Museum of Paris, said to have come from South America. In the 'Archives' of the museum, vol vi., for 1852, he redescribes and figures the species, observing that one of the specimens in the Museum was received from " Lieut. Maw." This must have been obtained from the Zoological Society, and is doubtless a fellow specimen to the one I described, and is said to have come from South America without any special habitat; and the other was brought by Captain Berard directly from the fresh waters of " Vera Cruz, Mexico." This species is very briefly and indistinctly described in both works, and the figure is by no means good. Probably M. Berard's specimen must be in a bad state ; for the shell is described as covered with fine "irregular rugosities." The indications of division of shields, especially the dorsal ones, are very indistinct. He figures the mouth, showing the alveolar surfaces of both jaws (t. xv. f. 4), but does not describe it. In the form of the mouth and the obscure streak from the back of the head, and the gular plate showing no indications of a central suture, it agrees with the specimen now in the Zoological Gardens, but is evidently an old specimen, while that which we have is young. M. Dumeril does not take any notice, either in the description or figure, of the existence of any sterno-costal shields; indeed the sutures of them seem to be entirely obliterated in the aged specimen he figures; and he separates it from the Emys trivittata (that is, an Indian Batagur) by the absence of the three black bands and the difference of its origin. Professor Owen in 1853, in the 'Monograph of the Fossil Chelo-nians of the Wealden Clay and Purbeck Limestone,' published by the Palfeontological Society, published a genus under the name of Pleurosternon, which he characterizes thus : - " Testa depressa, lata, complanata; sternum integrum, ossibus undecim compositum, per ossicula marginalia cum testa conjunctum, scutis submarginalibus inter scuta axillaria et inguinalia positis." He does not make any reference to m y genus Dermatemys; but the character here given is the exact counterpart, though in other technical terms, of that genus which was published four years previously; but in the description of one of the species he observes :- " In addition to the axillary and inguinal plates there are three |
