A DESCRIPTION OF THE GENUS DIMETRODON, COPE. 51 



The coracoid (PL III, Fig. 30) is small, quadrate in outline, with a thin anterior 

 edge. The lower edge is thickened and deeply notched near its posterior angle. The 

 portion anterior to the notch was considered by Cope as the procoracoid. The posterior 

 edge is concave from behind forwards and becomes swollen in the region of the scapular 

 articulation. The union of the scapula and the coracoid was accomplished only late in 

 life and was probably never perfect. 



Measurements. 



M. 



Total length of scapula and coracoid 276 



Total length of coracoid 067 



Total breadth of coracoid 058 



Total breadth of distal end of scapula 103 



Greatest extent of humeral face 069 



The femur (PL III, Figs. 36, 37) is a strong and heavy bone, with well-developed 

 articular surfaces. The proximal end is rounded posteriorly and deeply excavated 

 anteriorly so that it is crescentic in section. There is no distinct head, the whole proximal 

 end being rounded and thickened. There is a strong rugosity near the outer part of the 

 convex posterior surface. The shaft is roundly quadrate in section. The distal end is 

 divided by a deep groove into two strong rugosities, both bearing articular faces. The 

 inner is the shorter and extends inwards at a small angle to the shaft. The articular 

 face is almost entirely on the posterior surface and looks more backwards than downwards. 

 The face is elongated vertically and notched on its inner edge by an extension of the 

 popliteal space. The outer tuberosity is longer than the inner and is directed downwards. 

 It bears two articular faces, one on the posterior surface, looking almost directly back- 

 wards, is nearly square in outline, the other is apparently for the head of the fibula ; it is 

 largely on the lower surface of the tuberosity and joins the posterior face by a narrow 

 neck near its external side. 



Measurements. 



M. 



Total length 220 



Breadth of proximal end 073 



Breadth of distal end across condyles 069 



Greatest diameter of shaft at centre 036 



The humerus (PL III, Fig. 32) is without prominent condyles at the proximal end. 

 The articular face is a wide, concave area lying across the laterally expanded proximal 

 end at nearly a right angle. The inner angle of the proximal end is expanded into a 

 prominent tuberosity. The outer angle is thin, flattened antero-posteriorly and continu- 

 ous with the strongly developed deltoid ridge. The ridge stands at almost a right angle 

 with the proximal end of the bone. It becomes very prominent with a rugose surface 



