252 AMERICAN TESTUDINATA. Part II. 



Since I have h.ad an opportunity of comparing all the North American Testu- 

 dinata with one another, alive/ I cannot cease to wonder that the marked generic 

 peculiarities of the Emydoids should have been so entirely overlooked. I have 

 already stated (p. 246) that the so-called Cistudo Blandingii is a true Emj^s; it is 

 the North American representative of the common European Emys (Lutremys, Grai/.) 

 Now that its natural relations are accurately determined, it should henceforth be 

 called Emys Meleagris, as this specific name is older than that of BlandingiL But, 

 among the other North American Emydoids we find several other generic types. 

 Emys scabra (serrata), Troostii and elegans (cumberlandensis) constitute a distinct 

 genus, which I call Tkachemys ; whilst Emys mobiliensis, concinna (floridana), and 

 rugosa (rubriventris) constitute another genus under the name of Ptychemys; and 

 Emys geographica and Lessueurii (E. pseudo-geographica) still another under the name 

 of Graptemys. Emys picta, Bellii, and several new species, constitute also a distinct 

 genus, already recognized by Gray, and called by him Chrysemys. Emys guttata is 

 also the type of a distinct genus, which I call Nanemys. Emys Miihlenbergii is the 

 tyjie of the genus I have named Calemys, and Emys concentrica constitutes still 

 another genus, already named Malaclemys by Gray; tliis and Chrysemys being the 

 only ones thus far noticed as generically distinct from the other tyjies of Emy- 

 doids inhabiting North America. Emys reticulata constitutes also a new genus, 

 Deirochelys ; Emys insculpta another, Glyptemys ; and Emys mannorata B. and G. 

 (E. nigra, Hal.) still another, Actinemys. The North American Testudinina belong 

 to the new genus, Xerobates. All these new genera and several new species, 

 peculiar to the United States, are cliaracterized below. 



SECTION III. 



ESSENTIAL CHARACTERS OF THE ORDER OF TESTUDINATA. 



There is scarcely any order among Vertebrates so well defined and so naturally 

 circumscribed as that of the Turtles. The cycle of their modifications, notwith- 

 standing the diversity of sub-orders, families, and genera which they include, is so 

 narrow, the external systems of organs, even the proportions of the body, are so 



' The number of living turtles I had an oppor- friends in every part of the country ; and I shall 



tunity of examining and preserving for montlis and avail myself, in the next chapter, of tlie opportunity 



years in my yard, will appear incredible to Eu- duly to mention all tliese favors, when enumerating 



ropean naturalists. I have had them and their eggs singly all our species and the precise localities where 



by the thousands, thanks to the kindness of my they are found. 



