AND AVES OF NORTH AMERICA. 



I I 



Width at anterior point of splenial, 

 " near extremity, 

 " an inch behind fork, 

 " between rami at same point, 



Teeth opposite symphysis, 



In. 



2. 



1.9 

 1. 



13. 



Lin. 



4 

 13 



The larger teeth are all broken, but one with fang exposed, would probably measure when complete 1 in., 10 lin. 

 The form of some of the smaller is well represented in Leidy's figures above cited; they are acuminate, strongly 

 incurved, of a full lenticular section, with an anterior and posterior raised cutting ridge, in the transverse plane of 

 the crown. The sides present numerous narrow weakly defined facets, and are in a half protruded one, finely striate. 

 The alveoli do not open on the horizontal plane of the inside of the mandible, but the latter is raised above them 

 for the posterior half of the symphyseal portion of the jaw ; the latter is more depressed towards the extremity. 

 Teeth from other specimens and localities exhibit marked characters. They are all much curved and slender conic, 

 and subcylindric ; the tip smooth, the remainder more or less extensively minutely striate, but not fluted or ridged. 

 The fang is slightly flattened. In T. neocaesariensis the crowns are relatively shorter, less curved and more obtuse; 

 in both the anteroposterior dividing ridge is well marked. Part of the teeth attributed by Leidy to Hyposaurus 

 belong here ; see synonymes. 



The muzzle of a larger individual from Birmingham, accompanied vertebrae of this species, with a smaller gavial 

 cranium in fragments ; and a cervical vertebra similar to that described under Bottosaurus harlani. Its reference to 

 this species is not certain, but I give a figure of itr. 



The lateral maxillo-premaxillary suture is not preserved, so the number of prem axillary teeth cannot be exactly 

 ascertained; there are four to the line of the posterior margin of the large incisive foramen, of which the anterior is 

 quite small. The posterior palatal suture of the same element is prolonged in a narrow chevron on the median line 

 below, to opposite the eighth alveolus from the front ; there are nine alveoli behind this point, to the broken 

 extremity. A noteworthy character consists in the presence at the posterior part of the series of deep fossae 

 between the maxillary alveola; for the reception of the mandibular teeth, showing that the latter did not project 

 externally between the former, as in the existing gavial. The same structure appears in the smaller cranium which 

 accompanied it,* but is not found in the Thor. neocaesariensis. 



Fig. 19. 



Fig. 20. 



♦The fronto-parietal reeion of this one is described under head of n. brevispints. 

 AMERI. PHILOSO. SOC. — VOL. XIV. 20 



