Chap. IL THE EMYDOIDiE. 351 



SECTION ^' 1 1 1 . 



THE FAMILY OF EMYDOIDvE. 



Since the genus Testudo of Linnaeus began to be subdivided into minor groups, 

 and before the family of Emydoidte was circumscribed within its present limits, 

 the fresh-water Turtles have been combined, by different authors, in various Avays 

 with one another and with the land Turtles.^ J. E. Gray tells us, that Th. Bell 

 was the first to consider them as a separate family,- distinct from the Triony- 

 chidae, which, five years later, are still united with them by Wagler.'' At that 

 time, however, Gray associated the Chelyoid^ with the Emydoidiu ; and though he 

 afterwards separated these two families, the Emydoidaj still include the Chelydroidai 

 and the Cinosternoidte in his latest publications.* Fitzinger,'' in 1826, and Wicg- 

 mann,'' in 1832, adopted also the family of EmydoidiO as distinct from the Trio- 

 nychidiv; or Chilotaj, while, in 1836, Canino" considers it as a sub-family of the 

 Testudinidns, as he calls the AmydjB, exclusive of the Trionychidae. In 1835, 

 Dum^ril and Bibron ^ unite the Emydoidag and Chelyoidaa as one familj-, under 

 the name of Elodites ; distinguishing, however, the Emydoidaj as Elodites Crj-pto- 

 deres, to which they still refer Chelydra and Cinosternum, from the Chelyoidae, 

 which they call Elodites Pleuroderes. 



Tliis is by far the most numerous family in the order, as it includes over 

 sixty well knoAVTi species ; it presents also the broadest range of differences in hab- 

 its, size, and structure. 



The body rests upon a very broad and long flattened surface. It is high, 

 and arched upward both lengthwise and crosswise, highest and broadest about the 

 middle. The median longitudinal arch is not regular, but descends more steeply 

 as it approaches the ends ; the sides, too, curve more sharply around tlie ends 

 than about the middle ; the outlines, however, have no well defined angles so com- 

 bining as to divide the body into distinct regions, but run gradually into one 

 another, and the wliole carapace is like an overturned elongated bowl. The pla.s- 



1 Comp. Cliapt. K Sect. 2, p. 241. ■• Cat. Brit. JIii?. 1844. 



* See .J. E. (Irav's frcncia of Reptiles in Ann. of * Xcue Cla.ssif. der Kcptilieii, 1820; under the 



Philos. 1825, vol. 10, p. 210, wIk re llial lamily name of Eniydoidea. 

 name is spelled Eniydidiv. Bell also writes it Eiiiv- ' Haiidli. d. Zcml. 1832. 



dida^ in tlie Zool. .louni. lS2.'i. vol. 2. p. .■102. " C'lulon. Tal>. Anal. IS.'iG. 



' Naliirl. System der .Vniplilliien. 18o0. =• Erpet. tn'-ni'i-. \i<\. 2il, IS.'l."). 



