176 Dr. J. E. Gray on American Emydidse. 



XVII. — Notes on American Emydidse, «n</ Professor Agassiz's 

 Observations on my Catalogue of them. By Dr. J. E. Gray, 

 F.R.S. &c. 



Professor Agassiz, in the appendix and errata to his " Essay 

 on the North-American Tortoises," in the ' Contributions to the 

 Natural History of the United States of America,' published in 

 3857, observes : — 



" Ptychemys concinna is mentioned under four different names 

 by Dr. Gray — as Emys ornata, E. floridana, E. annulifera, and 

 Pseudemys concinna. Ptychemys mohilensis appears twice — as 

 E. mohilensis and E. ventricosa. Ptychemys rugosa also appears 

 twice — as E. rivulata and Pseudemys serrata. These facts are 

 sufficient to show that Gray's genus Pseudemys is not well 

 founded, as the two species which he himself had an oppor- 

 tunity of examining are only varieties of other species which he 

 refers to the old genus Emys. I am unable to refer his Emys 

 callirostris with certainty, as his figure, though well drawn, 

 does not exhibit the generic characters. I believe it, however, 

 to be one of the many varieties of Ptychemys concinna. The 

 same remark applies to Emys venusta" (vol. ii. p. 641). 



These observations are only founded on an examination of 

 the figures, and not on the specimens themselves, and, as I 

 suspect, on but a cursory study of the descriptions, — which may 

 be an excuse for their inaccuracy; but that is a reason why 

 they ought not to have been made. It is very true that the 

 figures of the entire animal do not and cannot " exhibit the 

 generic characters " used by Professor Agassiz, which are founded 

 on the ridges on the roof of the palate, and can only be seen in 

 a figure of the skull. The observation that these species appear 

 under more than one name is either a disingenuous statement 

 or one that neither Professor Agassiz nor any one else, from the 

 imperfection of the specimens, can confirm or contradict with 

 certainty : consequently any careful zoologist would be very 

 averse to giving an opinion on such a subject, unless he could 

 examine the specimens on which the species are established. 



I am satisfied that if Professor Agassiz had examined the 

 specimens of Emys ornata, he would himself allow that it not 

 only is not a variety of Pseudemys concinna, but that it does not 

 belong to the same genus. Pseudemys concinna belongs to his 

 genus Ptychemys, and Emys ornata to his genus Trachemys, ac- 

 cording to his characters. I only know Emys floridana, as stated 

 in the Catalogue, from Holbrook's figure, and quote it as such ; 

 but I am still not satisfied that it is the same as E. concinna. 

 As to E. annulifera, that is only founded on a very young speci- 

 men, which differs in the pattern of its colouring from all the 



