426 CHELONIA. 



ble, composed of numerous muscles, though not exsertile, and filling 

 altogether the lower floor of the mouth. The eyes are provided with 

 distinct eyelids, and the drum of the ear or tympanum is either visible 

 exteriorly or hidden under epidermic plates. The legs are short, 

 thickish, and variously constructed, according to habits. The tail is 

 subconical, and the vent or cloacal aperture circular. 



The Chelonians are oviparous: the eggs, once laid, receive no further 

 attention from their parents ; the young, therefore, are left to their 

 own care. They have numerous enemies in the shark and other car- 

 nivorous tribes, of which a large number become an early prey. 



In the newly just-hatched young, the carapax is longer than broad 

 in the sub-order of Chelonii, whilst it is circular in that of Testadinata. 

 In the Chelonii also, the snout is more acute, and the upper jaw pro- 

 vided above with a pointed process, which disappears gradually during 

 ulterior growth : the Testado nasicornis, of Lacepede, and the " Rhino- 

 ceros Turtle," of Shaw, allude to that transient peculiarity. 



As a question of nomenclature, we do not see the propriety of re- 

 taining the name of Testadinata to designate this Order. True, it is 

 older than that of Chelonia, but Klein,* w^ho was the first using it as 

 a prefix to the Turtles, did not characterize the latter as a natural 

 group ; and moreover, the terrestrial species being enumerated first on 

 his list, if the name is at all to be preserved, it will naturally revert 

 to the sub-order including those species. 



Alex. Brongniartf established the order of Chelonians upon a scien- 

 tific basis, and his name is the one that ought to be retained. 



It is preposterous, at any rate, to use the name of Testudinata in one 

 sense, and that of Chelonians in another sense, in speaking of these 

 Reptiles.J 



Wlien the law of priority, in regard to scientific nomenclature, can- 

 not be strictly enforced — and such is the case for a good many names 

 of divisions higher than genera — it becomes the duty of the naturalist 

 to select such names as may embody some philosophical idea, or recall 

 to mind some historical fact, afibrding a safe guide towards further 

 progress. 



Thus, if it be admitted that the Reptiles under consideration were 



* De Quadrupedum dispositio brevisque historia naturalis, 1751. 

 f Bulletin de la Societe Philomatique de Paris, 1800, 89. 



J Contributions to the Natural History of the United States of America. I, 1857, 

 235 (note). 



