150 University of Kansas Geological Survey. 



ess is gently inclined toward the radial side. On the dorsal 

 surface, a little distad and laterad of the middle, there is a 

 small roughening for muscular attachment. The same process 

 seems to be apparent in most of the genera, and may be called 

 the deltoid tubercle. 



Tylosaurus proriger. The humerus of Tylosaurus is the most 

 elongate and least expanded of any of the Kansas forms, and is 

 relatively the smallest. Its proximal end, unlike that of the 

 other genera, save Brachysaurus, is not transverse, but strongly 

 angulated a little to one side of the middle, its thinned border 

 sloping sharply away to meet the radial border in a rounded 

 angle about opposite the proximal fourth of the bone. The 

 ulnar side of the proximal border is moderately thinned and 

 slopes gently, and is more expanded than the radial side. The 

 distal border is much thicker on the radial side, the ulnar side 

 being thinner and only moderately expanded. The radial angle 

 is thin and very slightly produced ; it has no projecting proc- 

 ess. The ulnar angle, though more prominent, has no thick- 

 ened process. The free radial border is long and gently 

 concave between the proximal and distal rounded angles ; that 

 of the ulnar side is longer and deeper, but, like the other, is 

 nearly uniform in curvature, much more so than in the other 

 genera. The pectoral process is less projecting than in the 

 other genera, its cartilaginous surface smaller and situated 

 more nearly the proximal end. The rounded ridge which it 

 forms is situated nearly in the longitudinal axis of the bone, 

 and in line with the radial thickening of the distal end. 



Radius. 



Blosasaurus horridus. The radius in this species, as in all the 

 other species of the group, is much the larger bone of the fore- 

 arm. It is very stout at the proximal end, broadly expanded 

 at the distal. In the single specimen of this species known to 

 me the outer part of the bone is missing. The inner part dif- 

 fers from the corresponding bone of Clidastes in the distal angle 

 being more produced. 



