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Show 746 MR. P. L. SCLATER ON ANIMALS IN THE MENAGERIE. [Dec. 5, pl. iv. fig. 2) most clearly figures a double beard in P. expansa. Thirdly, Dumeril and Bibron (Erp. Gen. i. p. 584) give as a generic character of Podocnemis "deux barbillons sous le menton," and again speak of these (ibid. p. 385) in describing P. expansa. Fourthly, Peltocephalus, according to the best authorities, has no chin-beard at all. So that I do not think it can be truly said that the one-bearded chin is a character of the family Peltocephalidae. As regards the question whether P. unifilis in the stage described by Prof. Troschel (with which the specimen now before m e agrees very exactly, except that the spots on the head are bright yellow, not white, the colour iu Prof. Troschel's specimen having been probably destroyed in spirit) is a good species, I have not been able to come to a very satisfactory conclusion. W e require more information concerning the history of the Amazonian Tortoises and their various stages before we can come to positive results on the subject. Dr. Peters some time ago informed me that he considered P. unifilis a good species, and had several specimens in the Berlin Museum ; and I see that he has recently recorded the occurrence of a Tortoise on the Ucayali under this name*. Mr. Edward Bartlett informs me that he believes that he met with four species of the genus Podocnemis during his Amazonian travels, namely :- 1. The Tartaruya grande or Cherapa grande, which is " common all over the Amazons, and grows to a length of 2 feet or more, and lays from 100 to 150 soft round eggs, generally in steep sandbanks." This is no doubt Podocnemis expansa (Scbweigg.) ( = Emys amazonica, Spix), Dum. et Bibr. ii. p. 585. There can be no question, I think, that this species always has two barbules under the chin. Spix, it is true, says of it "gula unicirrhosa;" but Wagler, who figures from Spix's specimen, as I have said above, gives two. 2. The Cherapilla, a smaller species, found on the Huallaga and Ucayali. "It grows to a length of not more than 18 inches, and lays from twenty to forty eggs in rather a deep hole on flat sandbanks." The eggs, of which I exhibit Mr. Bartlett's specimens, are oval, and their shells quite hard; they measure 1*8 in. by 1*35. This I suppose to be Podocnemis dumeriliana (Schweigg.) or Emys macrocephala of Spix. Whether this species has one or two barbules ou the throat I cannot quite decide. A fine dried specimen (measuring about 16 in. in length of the upper shell) which Mr. E. Bartlett has lent to me has certainly only one central barbule. But in the figure of tbe head of P. dumeriliana given by A. Dumeril (Arch. d. Mus. vi. pl. xviii. fig. 3) two barbules are plainly shown. Dr. Gray has pointed out the differences in the form of the ridges on the alveolar surface of the upper jaw which separate this species from P. expansa, and which are well shown in the four skulls now exhibited from Mr. E. Bartlett's collection. But Dr. Gray has not remarked on another still more characteristic point * Monatsb. Ac. Berl. Aug. 3, 1871. |