190 FOSSIL REPTILES. 



in the marshes ; and when these dry up, what remains of 

 water in the bottom is so completely filled with them, that no 

 liquid is to be seen. It is thought that, at this time, the large 

 devour the smaller. They cannot re-ascend the river, because 

 the island is surrounded with salt water. Those of Guiana, 

 according to Laborde, sometimes remain almost dry in the 

 marshes, and are then considered most dangerous. 



The Cayman, with hony eyelids, {C. Palpebrosus,) is the 

 third species of M. Cuvier. In this he has established two 

 varieties. Of the first, of which he received specimens from 

 Cayenne, the following is a summary of the characters : — 



The muzzle is a little more elongated and less depressed 

 than in the preceding species. The surface of the bones is, 

 however, equally vermiculated. No osseous band unites the 

 orbits, but the upper lid is entirely filled by an osseous plate, 

 divided into three pieces by sutures. The nape is armed with 

 a range of four small scales ; then come four transverse bands, 

 each being provided with two projecting ridges, and they join 

 those of the back. The cranium is not pierced, nor are fora- 

 mina observable there at any age. There are twenty-one 

 teeth below on each side, and nineteen above. The interval 

 between the two external toes behind is obviously less pal- 

 mated than in the preceding species, which renders the ani- 

 mal, according to M. Cuvier, more terrestrial. Cayenne is 

 assuredly the country of this variety, to which the Baron 

 appears to restrict the epithet Palpebrosus. 



From four other specimens this eminent naturalist forms his 

 second variety. The characters are : — 



Osseous lids like the preceding : a ridge proceeding from 

 the anterior angle of the orbit. A small emargination at the 

 posterior edge of the cranium. The second band of the nape 

 wider than the others, with two or three small ridges irre- 

 gularly arranged ; the large ridges cut into scalene triangles, 

 greatly raised, which give a very bristling appearance to the 

 nape. The ridges of the back and tail also project very 

 much. 



