140 MEMOIRS OP THE UNIVERSITY OF CALIFORNIA. 



together with all of the pelvic elements, and the first two segments of the pos- 

 terior limb. 



Over thirty vertebrae are present with this specimen, the number being 

 about evenly divided between presacrals and postsacrals. They have been but 

 little disturbed, but are so turned that measurements of their height cannot 

 be made in most cases without destroying neural arches or ribs. The length 

 and height of a dorsal about fifteen vertebrae in front of the pelvis are nearly 

 the same as in the type specimen of S. oNiitoiiti. The anterior caudals are 

 much shorter than the corresponding centra of D. i>en-nii. A comparison of 

 the vertebrae of this form with S. pod/icus is difficult, as the portion of the 

 vertebral column represented in that species is here covered by the ribs. The 

 neural spines of the most posterior dorsals are, however, much like those in 

 the type specimen of S. pacificus. The pelvis so far as known is quite differ- 

 ent from that of S. pacificus. 



Short caudal ribs and long-spined Y-shaped chevrons are present on the an- 

 terior caudal vertebrae. 



MEASUREMENTS OP VERTEBRAE, SPECIMEN 9608. 

 Anteroposterior diameter of the centrum of a posterior dorsal about 



fifteen vertebrae in front of the pelvis 32 mm. 



Height of 15th centrum in front of pelvis 69 



Height of a neural arch about seven vertebrae in front of the pelvis (Hi 



Anteroposterior diameter of an anterior caudal centrum immediately 



behind the pelvis 32 



Height of neural arch of anterior caudal immediately behind the pelvis 52 

 Length of an anterior caudal chevron a 114 



a Approximate. 



The coracoid of the type specimen of S. osmonti is characterized by its 

 thickness, and the extreme narrowness of the proximal portion. The form 

 of the scapula is much like that in some mosasaurian genera. The greatly ab- 

 breviated and thickened elements of the anterior limb, though shorter and 

 thinner than in S.' alexandme, are easily distinguished from the corresponding 

 elements of S. careyi, which are much more specialized in these particulars. 



Near the humerus in specimen 9081 is a row of three paddle bones from 

 the rnesopodial or phalangeal. region (pi. 15, fig. 4). Two of them are of nearly 

 equal size, and the third element, at one end of the row, is much smaller. As 

 has been stated elsewhere (p. 72) there is reason to suppose that the rela- 

 tively large size of the anterior elements of the limb was accompanied by re- 

 duction of the posterior elements to such an extent that the limb came to have 

 only three digits, the most posterior of which was relatively small. 



Other discoidal paddle bones are present with specimen 9081 , and in one of 

 these the margin is distinctly pitted and grooved (pi. 15, fig. 3). 



