Case and Williston — Description of Reptilian Skulls. 315 



jaw there is a low, slightly rugose ridge which appears to mark 

 the portion of a suture which has closed. If this is true, the 

 portion of the bridge behind the rugose line may be the ante- 

 rior portion of the articular, and the anterior portion of the 

 bridge may represent the prearticular ; the ridge may, however, 

 be only a surface for the attachment of muscles. The coronoid 

 is a very small bone visible on the inner side of the jaw. The 

 surangular behind and the dentary in front send processes up- 

 ward which aid in the formation of the coronoid process. The 

 sutures on the outer side of the jaw can not be made out except 

 where a break in one of the jaws shows that the suture between 

 the dentary and the surangular runs downward a little anterior 

 to the coronoid process. The articular face of the articular 

 has two deep parallel grooves which limited the motion of the 

 jaw to the vertical plane. There are fifteen teeth in the jaw. 

 The posterior one is small and conical ; the next eight have the 

 expanded form characteristic of the genus. The first four have 

 the chisel-like form of true incisors, the fifth is nearly conical, 

 the sixth has the crown slightly expanded and carries a single 

 median tubercle. The other have wide crowns with three 

 tubercles. The wear was on the outer side of the teeth in the 

 lower jaw and the inner side in the upper. 



Animasaurus carinatus, gen. et sp. nov. (Fig. 3.) 



The specimen consists of a fairly perfect skull (No. 1107 

 Mus. Yale Univ.). It is slightly injured in the anterior part so 

 that the premaxillaries, the anterior ends of the maxillaries and 

 the nares are lost. The anterior portion of the facial region is 

 crushed down upon the palate. The teeth are all destroyed, 

 but the outlines of the roots show them to have been trans- 

 versely expanded as in Diadectes. The condition of the speci- 

 men is such that the sutures can not be made out and the hard 

 matrix can not be entirely removed from the palate, but enough 

 has been taken away, aided by a fortunate break, to make the 

 structure evident. 



The superior surface of the sJcidl. — Due to the position of 

 the quadrate, the posterior portion of the skull is proportion- 

 ately much broader than in Diadectes though the occipital por- 

 tion is narrower. The surface is roughened by sculpture and the 

 development of tubercular prominences which recall those of 

 the genus Chilonyx. This appearance is heightened by the 

 position of the quadrate, which slants inwards instead of lying 

 nearly parallel to the lateral surface, narrowing the occipital 

 region. The parietal foramen is very large, approximately 

 20 mm broad by 25 mm long. This opening is farther forward 

 than in Diadectes, a line drawn through the posterior edges of 

 the orbits cutting through it at near the center ; in Diadectes 



Am. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 196.— April, 1912. 

 23 



