CROCODILIANS. 287 



the crown of the teeth is compressed, subincurved, and terminated 

 by an anterior and posterior trenchant and finely serrated edge, as 

 in the Varanian and many of the Thecodont Saurians. In the Croco- 

 dilus cultridens of the Wealden strata (PL 62 a, fig. 10) the crown of 

 the teeth is thicker than in the Argenton species, and the anterior 

 and posterior edges are unbroken ; a few longitudinal ridges traverse 

 the crown of the tooth of this species, which makes the transition to 

 the ordinary crocodilian teeth. 



In all the genera of Crocodilians the teeth of the upper and 

 lower jaws are so placed that their points, instead of meeting, 

 interlock. 



In all the species of each genus, the teeth are present in the 

 intermaxillary, superior maxillary and premandibular bones, and are 

 confined to those bones, the palate being edentulous. The teeth are 

 relatively larger and stronger in the Alligators and Crocodiles, than 

 in the Gavials ; they are almost always conical, and slightly recurved ; 

 the crown has generally a sharp border before and behind, and it is 

 longitudinally striated. 



The Alligator palpebrosus has nineteen teeth on each side of the 

 upper jaw and twenty-one teeth on each side of the lower jaw, making 

 eighty teeth in all. The second, third, seventh and eighth teeth are 

 the largest in the upper jaw ; and the first and fourth are the largest 

 in the lower jaw. This dental character will be expressed by the 

 following formula, which, to save space and prevent repetition of 

 words, will be used to express the dental characters in all the other 

 species of Crocodilians. 



Alligator palpebrosus, |fE2i=80. j%y'^''' =largest. 



The first ten or eleven teeth in this species are more pointed 

 and compressed than the rest, and are slightly curved, while the 

 others are straight. 



Alligator lucius, £^^=80 i, z^l\l', li IS ^^^^^g^st. 



Alligator sclerops, \lz.\l^2. i^''=largest. 



The teeth in this species are less unequal than in the Alligator 

 lucius : the fourth lower canines pierce the upper jaw in old 

 specimens. 



Alligator cynocephalus, 15=11= 74 J'-t—= largest. 



