I38 REPTILES AND BIRDS. 



The Alligatorid^e 



Include the Jacares, Alligators, and Caimans. 



The Jacares have the head oblong and depressed, with a ridge 

 across the face in front of the eyes ; teeth unequal, canines of the 

 lower jaw fitting into a pit in the upper jaw ; toes only partially 

 webbed, eyelids fleshy, nostrils separated by a cartilage. Five 

 species are described — namely, J. Jissipes, from tropical America, 

 six feet in length ; J. sderqps, from the Brazils ; J. nigra, also from 

 the Brazils ; J. pwiciulatus, with triangular oblong head, muzzle 

 elongated, thin and flat, with a rounded point in front, and a slight 

 enlargement behind the nostrils ; J. vallefrons, differing slightly from 

 the above — both natives of the Brazils. 



Alligators have the jaws oblong, much depressed, broad and 

 nearly parallel; forehead with a 'small longitudinal ridge between 

 the orbits ; feet fringed, toes half webbed, the outer toes free ; 

 nostrils separated by a bony septum rising from the upper edge, 

 muzzle lengthening with age. The species best known is Alligator 

 mississipensis, which is a native of North America; its average 

 length is six to seven feet, although Bartram informs us that in 

 Florida it has been found twenty-three feet long. A. palpebrosus, 

 A. sderops, A. punctidatus, and A. cynocephalus are natives of South 

 America; and A. Indus is found in the southern portion of North 

 America. 



The Caimans have the jaws oblong, depressed, rounded, and 

 swollen at the end, without frontal ridges or maxillary pits ; teeth 

 unequal, the lower canines fitting into pits in the upper jaw; toes 

 webbed. There are several species described— C. trigonatus, C. 

 palpebrosus, and C. goddeceps, all natives of tropical America. 



C. acutus is also found in Martinique and San Domingo; C. 

 rhombifor, in Cuba. 



The principal characteristics of the Alligatoridse are a head one- 

 third the length, a very short muzzle ; teeth unequal in shape and 

 size, the fourth lower tooth buried into the upper jaw when the 

 mouth is closed ; the first teeth of the lower jaw piercing the upper 

 at a certain age, so as to appear through. the muzzle when closed; 

 the hinder legs and feet rounded, having neither crest nor indenta- 

 tion on their edges ; the intervals of the toes more than half covered 

 with a short membrane, forming semi-palmated feet. 



It is generally admitted, as we have stated above, that there 

 are six species of this genera, all American, the type of which 



