652 



PROF. H. G. SEELEY ON THE REPTILE 



from the part of the plate on which it is situate ; it is somewhat 

 fractured ; but its height as preserved is nearly 2 J inches, and the 

 length of its base rather less ; it terminates towards the free extre- 

 mity in a sharp cutting-edge. Its thickness in the middle of the base 

 is inch; and it tapers upward and outward towards both margins. 

 It is defined at the base by a constriction which appears to separate 

 it from the plate from which it rises. It is scored with somewhat 

 irregular vertical vascular furrows. The corresponding plate at the 

 other end is much smaller, and is denned from the under articular 

 surface by a furrow ; and a similar furrow appears to mark its limit 

 on the upper surface, as though it did not completely cover the bone 

 upon which it rests. It is of ovate outline, 2 T 2 ^- inches long and 1J 

 inch wide in the middle. Its surface is undulating, as though the 

 free extremity, growing against another plate, had been forced up 

 into an elevation. It has the aspect of projecting on one side be- 

 yond the bone on which it rests, and is then sharply compressed, and 

 terminates in a cutting-margin which is convex in length. The in- 

 terspace between these terminal plates is rhomboidal, about 1 T 9 inch 

 in length, and is covered with conical tubercles, the largest of which 

 is y 7 ^ inch long and about | inch high. These tubercles are about 

 5 in number, the 3 largest being on one side. 



The next series of dermal bones are all longitudinally carinate. 

 They may, perhaps, be divided into such as have the base angularly 

 excavated, as though they were median bones of the dorsal or 

 caudal region, and such as have the base comparatively flattened ; 

 and in these latter the keel becomes greatly reduced in height: 

 these bones are probably lateral. Judging from the example of 

 Stagonolepis, I am inclined to believe that most of these plates 

 pertain to the tail. There are four plates, each about 2 T % inches 

 long, with an ovate base having a rough margin, rising into a sharp 

 cutting median keel about 2 inches in height, which has a ver- 

 tical sharp margin behind and a convex margin over the length 

 of the plate (PI. XXX. fig. 2). The sides of these plates are con- 

 cave from above downward, and convex in length ; but they are 

 all somewhat distorted by pressure. They thin away at the free 

 margin to about inch in thickness. Four other plates, also an- 

 gular on the underside, are much more elongated, and clearly over- 

 lap each other at one end, which may be presumed to be posterior. 

 The largest of these plates is 6| inches long, inch wide where 

 widest behind, and 2 j inches high in the highest part of the sharp 

 compressed keel. One side of this plate is moderately concave from 

 above downward; the other side is plano-convex; and posteriorly the 

 underpart of the bone has the aspect of being obliquely truncated — 

 a character which results from the posterior 2|- inches rising free 

 from the basal attachment so as to terminate in an upward and 

 backwardly directed spine, which overlapped the next succeeding 

 plate. The crest of the median ridge has a very slight sigmoid 

 flexure. Attached to this bone on one side is a small fragment 

 which appears to be a broken portion of the proximal end of the 

 dorsal rib. Other plates are somewhat flatter and relatively broader; 



