232 FOSSIL REPTILES. 



parts, teeth, &c. are similar. To discover the differences 

 required a more attentive examination, but they were all found 

 to be specific. The symphysis of the lower jaw is much less 

 long in proportion. It exceeds only by a tenth the length of 

 each branch. In the little gavial it exceeds it by one third. 

 In the great gavial it exceeds it by a fourth and more. There 

 must be a corresponding difference of proportion in the upper 

 muzzle, but as it is detached from the cranium it cannot 

 be given so exactly. The teeth of the lower jaw are regularly 

 and alternately longer and smaller, counting from the fourth; 

 so that the fifth is one half shorter than the sixth, the seventh 

 than the eighth, and thus in succession. In the gavials, great 

 and small, this regular inequality does not take place. The 

 teeth which follow the fourth are nearly equal, except such as 

 appear to have shot forth more recently. 



In the upper jaw there are at first, on each side, two small 

 teeth, then a very large one a little back, and the others are 

 nearly equal and short. In the little gavial there is at first, on 

 each side, a small tooth, then at some distance another small 

 one, then one a little larger, and the following are nearly equal, 

 but as long as those below. 



If the aperture observable in the figure be that of the exter- 

 nal nostrils, it is more broad,- less long, and placed more forward 

 than in the little gavial. If it be the incisive foramen, as might 

 be conjectured from the position of the head, the character 

 would be still more distinctive. 



What appears to be the foramen which the crocodiles have 

 between the parietal, the mastoid, and the anterior frontal, is 

 much larger than in the little gavial, although it has the same 

 form. It exceeds the size of the orbit, which does not even 

 take place in the great gavial, in which also this aperture has 

 more breadth than length. The reverse is the case in the 

 fossil. 



Seventy-nine vertebrae are to be reckoned in the fossil skele- 



