NORTH AMERICAN PLESIOSAURS 727 



The left ischium also is united with its ilium. The bones are some- 

 what concave longitudinally above, and considerably so from side to 

 side. The blade is thin. In front view, when articulated, the 

 interacetabular thickening lies nearly horizontal, with the acetabular 

 thickening lying above the transverse plate so that the acetabulum 

 looks upward and outward. Back of the thickening, the downward 

 curvature of the thinned part leaves an obtuse keel in the middle. 



Pubes. — The pubes are incomplete, but their outline cannot differ 

 materially from that of T. osborni. The right pubis is firmly attached 

 to the ischium in its natural position. The sutural border is but 

 little more than half the length of the acetabular border; thence to 

 the symphysial angle the curve is smoothly and deeply concave, the 

 immediate border for the most part somewhat thinned, though the 

 bone is thickened a little in front of it. The external border, thinner, 

 is not evenly concave as in T. osborni, but is sinuous, with a convexity 

 in the middle of the concavity. The anterior external angle is some- 

 what thickened and rounded. Of the thin anterior border a part has 

 been lost. The symphysial border is squarely truncated, showing a 

 horizontal union. The upper surface of the bone is strongly concave, 

 the external angle turned upward at about thirty degrees from the 

 horizontal part. As is indicated in the pelvis of T. osborni, the 

 whole bone turns downward distinctly from the plane of the ischium. 



Width of pubes, from side to side, as articulated 682 mm 



Antero -posterior extent of pubis, approximated 403 



Width of neck of pubis 157 



Length of symphysis 255 



Length of ischium 600 



Expanse of ischia 630 



Paddles. — Parts of three paddles are preserved, one of them nearly 

 complete, though, unfortunately there is no complete propodial 

 among the material. 



The proximal articular surface of the humerus forms nearly a 

 hemisphere, the pitted cartilaginous surface limited sharply by a 

 distinct rim. The tuberosity stands out prominendy on the dorsal 

 side, its top only has a distinctly Hmited cartilaginous surface con- 

 nected with that of the head. The shaft below the head is 'somewhat 

 oval. The distal extremity of one propodial has the epi-, meso-, and 



