414 



AMERICAN TESTUDINATA. 



Part II. 



neck is shorter than in Clielydra ; this is owing to the size of the head ; for 

 such a head on a long neck would be cumbersome. The three ridges along the 

 carapace are largely developed, and neither of them vanishes with age. The mar- 

 ginal rim is thick, projecting far out beyond the carapace at the sides ; and at the 

 front end it is deeply arched backwards, which is necessary to allow free motion 

 to the large head. One scale covers the whole nose, above the horny sheath of 

 the jaw. There is a characteristic row of scales, three in number, situated between 

 the costal and marginal rows, over the union of the carapace and plastron, the 

 addition of which is perhaps due to the great thickness of the mai-ginal rim at 

 that place, and two scales on each of the bridges of the plastron, within the 

 row of three which crosses the ends. The whole neck and chin are covered 

 with horny papilla3 of various sizes and forms. 



Gypochelys lacertina, Ag} Sufficient references to this species have already 

 been given (p. 250). Its geographical range extends from western Georgia and 

 north-western Florida, through Alabama, Mississippi, and Louisiana, to Texas. But 

 I do not know exactly how far north it may be found in the valley of the 

 Mississippi. I have lately received another young specimen from the neighbor- 

 hood of New Orleans, through the kindness of Dr. Benedict, and compared other 

 specimens from Mississippi, sent by Professor Wailes to the Museum of the Essex 

 Institute in Salem, and also one belonging to the Museum of Oxford, Missis- 

 sippi. Mr. Robert H. Gardiner has sent me one from south-western Georgia. They 

 all agree in their generic and specific characters, and fully sustain the first 

 observations of Dr. Ilolbrook.^ According to Professor Wailes, it measures some- 

 times three feet in its greatest diameter. I insert below some interesting remarks 

 resp,ecting its haljits, which have lately been communicated to me by Eev. Edw. 

 Fontaine, of Austin, in Texas, who first observed it in that State. 



" I often have encounters with them when fishing for bass in our prairie 

 rivulets. I saw one Ijang dead on the margin of a lake in Panola County, 



* As this species is unquestionably the Clieljdra 

 lacertina of Sehwei>Tgcr, (Prodi-., q. a.,) the specific 

 name of Gyp. Temminckii, proposed by Troost and 

 Dr. Holbrook, and adopted, p. 248, must give 

 way to the older one, introduced by Schweigger. I 

 am well aware that Dumeril and Bibron distinctly 

 state (Erp. gen. vol. 2, p. 354) that Clielydra lacer- 

 tina, Schw., is only founded upon an overgrown speci- 

 men of Chelydra serpentina ; but these very specific 

 names show that Schweigger not only knew the two 

 species of Chelydroids which inhabit the United 



States, but also perceived the differences in the scales 

 under the tail, which distinguish them, and upon 

 which I have insisted, (p. 412,) as generic characters ; 

 and that he was aware how these peculiarities com- 

 pare with the scales of Serpents and Lacertians. 



^ North American Herpetology, vol. 1, p. 147, 

 pi. 24. Dr. Holbrook describes it under the name of 

 Chelonura Temminckii ; Dumeril, Cat. Rep. of the 

 Jardin des Plantes, calls it Emysaurus Temminckii, 

 adding, that he had already distinguished it in his man- 

 uscript, as E. lacertina. Compare, however, note 1. 



