196 C. W. Gilmore — New Species of Baptanodon. 



brae into the lower lobe of the caudal fin. In Ichthyosaurus 

 communis, Owen determined that the downward trend of the 

 vertebrae commenced with the eightieth centrums and Mr. 

 Iieecl informs the writer that as found in the ground this 

 specimen showed such a bend beginning at the point where 

 the caudals decrease in size so rapidly. 



Anterior limb.- — Figure 1 illustrates the left pectoral ex- 

 tremity as preserved with this specimen. All of the elements 

 remaining were retained in the matrix, and thus afford a good 

 opportunity to study their mutual relationships. 



The robust humerus has a stout twisted shaft and expanded 

 ends which are so turned as to cut each other at an angle of 



Fig. 1. Left pectoral extremity of Bajitanodon reedi, seen from below. 

 One-fifth natural size. H, humerus ; R, radius ; U, ulna ; P, pisiform ; Ea, 

 radiale ; I, intermedium ; Ul, ulnare. Type specimen in the University of 

 Wyoming collection, Laramie, Wyoming. 



45°. The proximal end is subrectangular in outline and very 

 rugose. It is slightly convex both vertically and horizontally. 

 Vertically this end has an average thickness of about 80 mm . 

 The distal end is much compressed, being about 50 mm in thick- 

 ness, but broadly expanded in the other diameter. This end 

 presents two distinct faces for articulation with the elements 

 of the epipodal row. The facet for the radius has a markedly 

 concave border instead of the straight face observed in the 

 other species. The facet opposed to the ulna and pisiform 

 meets the facet for the radius at an obtuse angle and from 

 there extends straight out to the edge of the humerus. It is 

 quite probable that these facets are concave vertically as found 

 on the humerus of B. marslii^ but to determine this point it 

 would be necessary to separate these elements, aud their closely 

 applied surfaces rendered this procedure inadvisable. 



The main projection of the proximal end beyond the plane 

 of the distal end is toward the upper side, thus forming a very 



