726 5. W. WILLISTON 



parts of the coracoids are broadly separated, their early, normal 

 condition. The interclavicular foramen is a relatively late develop- 

 ment, reaching its highest extreme in this genus and Polycotylus. 

 Such a foramen, imperfectly understood, occurs in Muraenosaurus, 

 and in a species described by me from the lower Cretaceous of 

 Kansas provisionally, but incorrectly referred to Plesiosaurus."- 

 What its function was it is difficult to say, if it had any, and its 

 well-formed and thickened borders suggest that it did have some 

 function. 



Length of interclavicle 224 mm 



Expanse of interclavicle 166 



Width of foramen 33 



Length of foramen 90 



Length of clavicles 410 



Pelvis. — ^The pelvis, though incomplete, has no distortion or mal- 

 formation. The larger part of each ischium is present, the two united 

 in the median hne, and the left one has the ihum attached. The 

 right ihum is quite perfect. Its upper extremity is flattened from 

 within outward, and has a roughened surface on the inner side near 

 the end for hgamentous attachment to the first of the sacral ribs. 

 Below, the shaft is thicker, at its middle forming nearly a circle in 

 cross-section. The lower extremity is thickened, club-shaped, with 

 a large, flat, articular surface, broadly oval in shape, the anterior 

 broad part looking more directly downward for the acetabulum; the 

 posterior, more obHquely placed, smaller and subtriangular in shape, 

 for articulation with the ischium. The anterior border of the bone is 

 concave, with a slight convexity above, and a strong convexity at the 

 lower end. The posterior border is convex except at the lower 

 part, where there is a concavity. 



Length of ihum 323 mm 



Diameters of shaft at middle 37, 53 



Greatest diameter of lower extremity 82 



Antero-posterior diameter of lower extremity 100 



Ischia. — The ischia are shaped very much as in T. osborni, that is, 

 elongate and narrow, a characteristic of the group. Both ischia are 

 present, attached to each other, and, as already stated, to the pubes. 



I Loc. cit., p. 44, Fig. II. 



