354 KANSAS UNIVERSITY SCIENCE BULLETIN. 



edge of the dentary is oblique and the lower edge is cut off by 

 this. The posterior of the dentary is forficate and sheaths the 

 anterior projection of the articulare. The greatest thickness 

 of the dentary is along the median line. Ventral to this it is 

 inclined rapidly inward. Dorsal to the median line it is rapidly 

 depressed and the outer line of the teeth falls inside of the base 

 line of the inner face. This upper depression is posterior to 

 the canine teeth, as they are located where the mandible is 

 rather thick. The outer face is marked by several foramina. 

 Just below the median line there are four. In the depression 

 below the teeth there are two of noticeable size at the anterior 

 part. There is also a foramen in the posterior end of the lower 

 fork of the dentary. The whole face is striated and marked 

 with small holes. At the base of the anterior teeth there is a 

 pit. The ventral line is almost straight, but at the anterior end 

 it is curved upward, making a protuberance for the chin. 



The inner face is rather plain and is striated. This face is 

 one plane for the most part. At the middle of the upper part 

 the face is drawn inward so that the teeth are inclined in- 

 ward. The front is beveled and forms the symphyseal sur- 

 face. This is formed at the expense of the inner face. Back of 

 the teeth the face is cut out, making the large hollow in the 

 mandible. There is a cavity extending anteriorly into the bone. 



The dentary has but two articulations. It meets the other 

 dentary in front, and at the posterior articulates with the ar- 

 ticulare. The dentary sheaths the articulare. 



Articulare. (Plate XXXVI, figs. 61, 62, 63.) 



The articulare is a triangular bone, thick posteriorly and 

 very thin anteriorly, making it wedge-shaped, the anterior 

 point being in the fork of the dentary. The outer face is 

 rounded and is striated. The ventral face is wedge-shaped 

 and rests on the dentary. At the posterior it drops down and 

 makes an articulating surface for the angulare. 



The dorsal part is extended upwards in a projection and 

 helps to make the coronoid process. At the posterior end the 

 bone is thick and has articulating surfaces for the quadrate 

 and angulare. Immediately in front of the articulations with 

 the quadrate the bone becomes thin. The ventral face of the 

 articulare, although wide, may be called a shelf, as the upper 

 edge is thin in a horizontal plane. 



