16 NEW REPTILES AM) BTEGOCEPHALIANS KKOM 



The transverse bone, if present, i> a small element. On each side there is an uncer- 

 tain line, indicated in figure 1 b, which seems to mark the separation of a distinct element 

 from the pterygoid. On the right side the small element is slightly displaced, indicating 

 its distinct character. 



The maxillaries appear on the lower surface as a tooth-bearing edge only. There 

 are no tusks. The bone of the right side, which is complete, carries 97 teeth and spaces; 

 allowing for the small pari missing on the left side there would be 98 on that side. These 

 numbers were certainly not a fixed quantity in the individual or species. 



The parasphenoid has a broad, flat processus cultriformis, which terminates at 

 the anterior end in a sharp point extending far forward between the vomers. In the 

 specimen the anterior end is raised, so that there is a decided elongate pit on the roof of 

 the mouth. This seems to be entirely natural, but may be due, in part, to slight post- 

 mortem changes. The posterior end is moderately expanded and meets the pterygoids 

 in long, clearly marked sutures. The central part of this expanded portion is marked 

 by low but distinct rugosities. Near the posterior end there is a low elevation on each 

 side, which runs from the pterygoids out upon the parasphenoid and then turns sharply 

 to the rear near the median line. The sutures with the exoccipital run obliquely back- 

 ward and inward and almost, but not quite, meet at the bottom of the notch between 

 the exoccipitals. These sutures are very complex and sharply and finely interdigitating. 



No trace of a basioccipital or basisphenoid could be made out on the specimen, on 

 either the upper or the lower side of the floor of the brain- case, or by a careful examination 

 of the edges of broken pieces in the process of preparation. 



The pterygoids. — There are two strong rami of the pterygoids visible on the lower 

 surface. The anterior runs forward and outward to join the palatines and the trans- 

 verse (?) or maxillary. There is a slight median depression on this ramus, and near 

 the anterior end there is a small prominence extending slightly downward and outward. 

 The second ramus runs directly outward to the quadrate; its lower surface is rounded. 



The quadrates. — The articular surface is concave from side to side and convex in its 

 longest diameter, which runs obliquely from without, inward and forward. The inner 

 and outer edges are raised into slender, sharp ridges. The suture between the quadrate 

 and the quadratojugal is not clearly marked, but it was evidently at the extremity of a 

 process extending inward from the quadratojugal. Anteriorly the quadrate sends a 

 process forward and inward on the anterior face of the anterior rising process of the 

 pterygoid. Posteriorly the quadrate is overlapped by the conjoined outer ends of the 

 rising processes of the pterygoid. Between the quadrate and the quadratojugal there 

 is a relatively large quadrate foramen. As shown in figure 2 b, there is apparently 

 a small, distinct element present between the anterior rising process of the pterygoid 

 and the inner process of the quadrate. This may be a deceptive appearance, but it is 

 present on both sides and the lines between the elements are distinct and filled with 

 matrix. Its meaning is unknown; certainly it is not a part of a descending process from 

 the skull-roof, as the lower side of the roofing bones at this point is perfectly smooth. 



The exoccipitals carry the large, distinct condyles, which are separated by a deep 

 notch extending forward to the parasphenoid bone. There is a good-sized foramen on 

 the lower side of each, which probably transmitted the X and XI nerves and the jugular 

 vein. On the middle of the outer side is the foramen for the XII (?) nerve. At the 

 base of the rising process which articulates with the dcrmsupraoccipital and the tabulare 

 there is a large foramen on the inner side which transmitted the X nerve. 



The posterior jace of the skull (fig. 1 c, and plate 2, fig. a). — The dermsupraoccipitals 

 are visible in the median line and are separated by a distinct suture. They join the 

 tsbulan by straight vertical sutures. The space between the dermsupraoccipitals was 

 filled in large part by a mass of cartilage in the absence of a supraoccipital. 



