﻿ix, d, i Day: Ophiocephalus striatus 29 



articulate forward and on the outside with the palatines (2), 

 on the lower side with the pterygoids (80), posteriorly and 

 ventrally with the palatines (2), on the lower side with the 

 pterygoids (80), posteriorly and ventrally with the quadrates 

 (7), and posteriorly with the metapterygoids (8). They are 

 about as long as the palatines and about three-fourths as long 

 as the frontals (36). The outside of that of the right side is 

 represented in Plate VII and the inside of the left in Plate VIII. 



In Plate VIII the interior side of the left pterygoid (80) is 

 shown, and in Plate VII the exterior of the right. They artic- 

 ulate with the palatines (2) anteriorly, the posterior ends of 

 which extend into the anterior fossa in the pterygoids. The 

 posterior end lies inside of, and articulates with, the anterior 

 portion of the quadrates (7). The ventral margin of the meso- 

 pterygoids (71) lies internally to, and articulates with, the in- 

 terior and dorsal margin of the pterygoids. The anterior spinous 

 portion lies along the dorsal side of the palatines (2). At the 

 top of Plate VII the pterygoid is seen still articulated. 



III. MANDIBLE 

 PLATE IX 



The premaxillaries (1) are curved and tapering from the 

 middle region posteriorly, where they are cartilaginous and 

 almost spinous. At the anterior end is a dorsal process divided 

 into two parts, the more anterior being the higher. The shorter 

 sets just below the nasals (16), while the longer passes dorsally 

 through the opening between the nasals (16) and anteriorly to 

 the supraethmoid (75). The teeth anteriorly on the ventral 

 side are moderately large, while those posteriorly are very fine. 

 On the inside margin of the posterior two-thirds is a ridge of 

 cartilage which is continuous with a short ridge-like process 

 of bone, originating a short distance posterior to the dorsal 

 process. The premaxillaries articulate with the maxillaries (5) 

 anteriorly and posteriorly, lying ventrad to them. They articu- 

 late with each other anteriorly, and the higher dorsal process at 

 the anterior end of each overlies the anterior surface of the supra- 

 ethmoid (75). They lie laterad of the palatines (2) and the 

 pterygoids (80) , and the anterior end of each overlies the vomer 

 (67). (Plate I; Plate VI, fig. 1; and Plate IX.) In Plate IX 

 the dorsal side of the left and the central side of the right are 

 exposed. The left is also seen in Plate I. 



The left and right dentaries (3) are shown from the dorsal 

 side and the outer lateral side, respectively. They dovetail 



