AND AYES OF NORTH AMERICA. Width at anterior point of splenial, " near extremity, g an inch behind fork, " between rami at same point, Teeth opposite symphysis, 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 repirosented in Leidy's figures above cited ; they are acuminate, strongly ineurved, of a full lenticular section, with an anterior and posterior raised cutting ridge, in the transverse plane of the crowu. 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 symphyscal 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 fiatteued. 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 llyposaurus belong here ; see synonymes. The muzzle of a larger individual from Birmingham, accompanied vertebra?. of this species, with a smaller gavial cranium in fragments ; and a cervical vertebra similar to that described under Bottosaurus harlani. Its refereuce to this species is not certain, but I give a figure of it. The lateral maxillo-premaxillary suture is not preserved, so the number of premaxillary 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 brokeu extremity. A noteworthy character consists in the presence at the posterior part of the series of deep fossae Between the maxillary alveohe 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 iu the smaller cranium which accompanied it,* but is not found in the Thor. neocaesariensis. Fig. 19. Fig. 20. Lm C.. c...Tarcif-77at • The fronto-parietal region of this one is described under bead of IL brevispints. AMERI. PHILOSO. SOC.—VOL. XIV. 20
