280 



back of the middle and terminating in nearly flat articular fliccts fur a chevron. 

 The surface between these eminences forms a moderately deep concavity. 

 The measurements of the specimen are as follows: 



Lines. 



Lengtli of the body beneath 31 



Depth anteriorly 35 



Breadth anteriorly 42 



Mr. Truman's collection contains several t;eeth which may probably belong 

 to the same animal as tlie vertebra just described. 



The largest of the teeth is represented in Fig. 18, Plate XXXIV. It pre- 

 sents the usual mosasauroid form, being curved conical, with the inner and 

 outer surfaces unequal in extent and degree of convexity and separated by 

 acute ridges becoming more prominent near the apex of the crown. The 

 enamel is longitudinally striate, especially toward the base of the crown, 

 where more marked ridges show a tendency to divide the surfaces into narrow 

 planes. 



The specimen is a shed tooth, and measures a little more than 2 inches in 

 length ; and the diameter at base is about 14 lines. 



A second tooth, represented in Fig. 21, has nearly the same characters 

 as the former. It is smalle*, more compressed, so that its section is 

 more elliptical, and its inner and outer surfaces are more equal. It is also 

 a shed specimen, and measures IJ inches in length. Its base, an outline of 

 which is seen in Fig. 22, measures 10 lines fore and aft, and 8 lines trans- 

 versely. 



The third specimen, represented in Fig. 19, has nearly the same form as 

 the preceding, but has its surfaces distinctly subdivided into narrow, slightly 

 depressed, smooth planes, of which there are six externally and seven intei-- 

 nally. Transverse outlines of the base and of the crown a short distance 

 above are given in Fig. 20. The length of the tooth, also, like the other, a 

 shed sjiecimen, has been about 20 lines. The diameter of the base fore and 

 aft is lOf lines; transversely 8|- lines. 



Fig. 16 represents a small tooth, accompanying the former specimens, 

 which I suppose to be from the back pari of the series of the same spe- 

 cies as the teeth of Figs. 18 and 21. It is more curved in proportion 

 with its length than in these, but has nearly the same outline in trans- 

 verse section, and has the enamel striated in the same manner. Its length 

 when complete has been about an inch. Its diameter at base fore and aft 

 is 64 lines; transversely .6 lines. 



