418 



AMERICAN TESTUDINATA. 



Part II. 



SECTION VII. 



GENERA OF CINOSTERNOID^. 



Our knowledge of the genera and species of this family has progressed very 

 slowly. For a long time only two species were known, which remained mixed 

 up in the genus Terrapene with other sjiecies belonging to very different genera, 

 until Fleming distinguished the genus Cistudo, Spix the genus Cinosternuna, BeU 

 the genus Sternothserus, and Wagler the genus Staurotypus, among which all the 

 species thus far included in the genus Terrapene were at once divided, and new 

 ones added. But, even after this first repartition of the species into several 

 genera, much confusion continued to prevail in the nomenclature, as well as in 

 the characteristics, of these animals. The name Terrapene, introduced in our 

 science by Merrem, in 1820, to include all the fresh-water Turtles with a movable 

 sternum,^ was limited, in 1825, to the Box Turtle, Cistudo, by J. E. Gray,^ while 

 Bell still imited heterogeneous species under that name.^ About ten years later, 

 Canino applied the name Terrapene exclusively to the North American Emyds, 

 and very properly retained the name Emys * for the European species, to which 

 it had been applied from the time of the first dismemberment of the old Lin- 

 n«an genus Testudo. The genus Cinosternum was from the l^eginning circum- 

 scribed within natural limits by Spix,^ and maintained within the same limits by 



iKontogr., vol. 2, p. 238, pi. 26, 27, ami 30,) has the 

 front end of the plastron widened, as in Platysternum, 

 while the posterior end is pointed, as in Chelydra. In 

 Chelydra Dechenii, Myr., (Palseontogr., p. 242, pi. 28, 

 29, 30, fig. 5 and C,) the case is exactly reversed. It 

 is thus plain, that, while at the time of their first ap- 

 pearance upon earth the representatives of this fam- 

 ily were not constructed exactly as they now are, 

 they yet foreshadowed, in the combination of their 

 characters, the peculiarities that distinguish the living 

 genera, two of which occur in North America and 

 one in China, though none are found where the type 

 first originated. 



^ Besides two species of Cinosternoidw, (Terra- 

 pene Boscii and odorata, which are one and the same 

 species, now called Ozotheca odorata, and Terrapene 

 pennsylvanica and tricarinata, which are also identi- 

 cal, and belong to the genus Thyrosternum,) the genus 



Terrapene, as limited by Jrerrem, (in his Testamen 

 Systematis Amjihibiorum, Marburgi, 1820,) embraces 

 a genuine Sternotha^rus, Terrapene nigricans, and two 

 Cistudos, Terrapene clausa and amboinensis. 



^ Genera of Reptiles, in Ann. of Phil., vol. 10, 

 p. 211. 



' Monograph of the Tortoises having a movable 

 sternum, in Zool. Journ., vol. 2, 182.5, p. 299. In 

 this paper Bell still unites the European Emys with 

 the North American Cistudo as one genus, under the 

 name of Terrapene. 



* Chelon. Tab. Anal. 1836. In 1830, Wagler 

 had already retained the name of Emys for the Eu- 

 ropean species ; but, like Bell, he still associated with 

 it the Cistudos, which were at last duly distinguished 

 by Canino. 



^ Srix, (.J. B.,) Species novse Testudinum et 

 Ranarum, Monachii, 1824, 4to. 



