304 Causes which retard Zoological Knowledge. 



eighth time, under almost as many names, and has given a tole- 

 rable good figure ; he here calls it Chersina anguluta, having 

 previously described it as T. Bellii: vide Gray, spic. zool. t. 3. — 

 If the synonyma he quotes are to be depended on, then the real 

 Linnsean name of the species must be retained, bearing in mind 

 always, that the genus Chersina of Merrem, is only the old 

 genus Testudo, with the sternal plate slightly projecting ante- 

 riorly, and would include T. polyphemus of Bartram. 



Concerning the genus " Kimxys" of Bell, it may be remarked, 

 that, if the peculiarity noticed in the back-plate of the species 

 of this genus be not only accidental, as Baron Cuvier states it to 

 be, it can serve only to distinguish a variety common to two or 

 more species of testudo : and the genus " Pyxis" of Bell, also ap- 

 pears to us as representing a variety of the genus Cistuda, or 

 common box tortoise. 



The very natural genus Cistuda, first established by that sen- 

 sible and classical naturahst, Mr. Fleming, (Vide Philos. of 

 2iOol.) and adopted by Mr. Say two years subsequently, (Vide 

 Jour, A. N. S. vol. iv.) Mr. Gray places in the family EMYDiE, 

 and represents these animals " as living in ponds and ditches, 

 only taking their food while in the water," and thinks he has 

 observed 36 species, 18 of which come from America; (vide p. 17.) 

 The cistuda clausa, or common " box turtle" of North America, 

 possesses none of the habits above enumerated, but is in every 

 respect a " lajid tortoise" which is the name by which this ani- 

 mal universally goes by in this country; and Mr. Say remarks, 

 very judiciously, (vide Long's 1st Exped.) that he examined this 

 species as it came under his observation throughout the country, 

 from the shores of the Delaware to the base of the Rocky 

 Mountains, and could detect only a single species, presenting 

 many varieties in colour and markings. In like manner, the 

 Testudo trifasciata of Bell, or Cistuda trifasciata. Gray — is a 

 variety of Cistuda clausa of other authors. 



Mr. G. is most fruitful in synonyma : the land-tortoise of Eu- 

 rope, so familiarly known, is dignified by ten titles, not doubting 

 but that it possesses legitimate claims to all of them. 



The genus Emys of Gray, only differs from the other species 

 of this genus, as adopted by other authors — and from which this 

 is taken — in having the back and breast-plates united by solid 

 (not osseous) symphysis; the habits and general organization be- 



