NORTH AMERICA AND THEIR VERTEBRATE FAUNA. 



i6s 



ERYOPS. 



Although so much has been written about this genus the collection 

 permits a few new points to be added. 



The interdavicle and clavicle have been known from almost the first dis- 

 covery of the genus, but have been found preserved in such refractory matrix 

 that the exact character of the sculpture has not been clearly seen. The 

 specimens from the Brier Creek bone-bed are so well preserved and naturally 

 cleaned that this character is beautifully shown. The interclavicle (plate 23, 

 fig. i) is slightly imperfect, having lost some of the slender processes on the 

 anterior and posterior borders, but it is apparent that very little can be 

 missing. The posterior end of the clavicle (plate 23, fig. 2) is greatly fore- 

 shortened in the photograph ; the small patch of very coarse sculpture marks 

 the position of a sharp bend in the bone. 



The cleithrum (plate 23, figs. 3 and 4) has been known to exist, but no per- 

 fect specimen has previously been recovered. It is gently sigmoid in outline, 

 with the anterior two-thirds drawn out into a slender process nearly circular 

 in section. The distal end of this process is marked by strong, linear rugosities. 

 The posterior third is expanded into a scimitar-shaped blade, very thin on the 

 convex edge but thick at the point of union with the slender process. The thin 

 edges show some radial striations. The inner side of this portion is excavated 

 by a deep linear cavity, into which fitted the upper edge* of the scapula. 



Humerus. — A small humerus (No. 33 16, fig. j,S,a,b,c) is very probably that 

 of an immature Eryops. The articular faces are deeply concave, as if there 



Fig. 38. — (a) Anterior face, (i) posterior face, (c) outer edge of right humerus of an immature individual, 

 Eryops megacephalus Cope, No. 3316. X /j. 

 {d) Lower face, (e) upper face, (/) proximal face, (g) distal face of femur of an immature individual, prob- 

 ably Eryops{}), No. 3432. X ^3. (The original is broken and the figures {d) and (e) are somewhat 

 restored.) 



had been a large mass of cartilage attached. In general the form is that of 

 an Eryops htimerus, but the bone is proportionately shorter and heavier. The 

 ectepicondylar process is not separate from the distal articular face, and the 

 process on the dorsal surface of the inner edge of the proximal end is quite 



