136 AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



of the inner side of the bone. A third foramen is seen below the humeral 

 facet, opening on the inner side at the lower end of the vertical flexure. 

 This 'must be the true supracoracoid foramen, through which the scapula- 

 procoracoid suture doubtless passes. The true glenoid fossa is limited below 

 posteriorly by a strong declivity. The inner surface of the scapula above, 

 like the exterior, is nearly flat, the lower surface convex in front. Just 

 back of the glenoid cavity and corresponding to the vertical margin of the 

 outer side, the bone on the inner side turns abruptly out\yard, save on the 

 lowermost portion, bounding in front a posterior cavity into which opens 

 the supraglenoid and the supracoracoid foramina, above and below, as 

 shown by the arrows in the figure. In front of the border, the surface of 

 the bone is strongly convex from above downward, and somewhat so from 

 side to side. This surface is pierced near its middle by the glenoid foramen. 

 "No sutures are visible distinguishing the bone into ks three elements. 

 As regards the cleithrum, there is a total absence of all indications of such 

 a bone as occurs in Eryops, either on the upper or anterior border. 



''Clavicle and interclavicle: The right clavicle was found in the matrix 

 nearly in its anatomical position, its upper end only gone. It is very small 

 for an amphibian, and has lost every trace of the pittings so characteristic 

 of the stegocephalan clavicles on its outer surface, though not unlike the 

 clavicles of Eryops. (See Williston, Kansas University Quarterly, viii, 

 185, plate XXIX, fig. 2.) The clavicle is bent near the middle nearly at a 

 right angle, and somewhat twisted. The proximal part, underlying the 

 interclavicle, is but moderately expanded — less so, in fact, than in the con- 

 temporary reptiles, and not twice the width of the distal part._ Its ante- 

 rior border is thickened, its posterior, somewhat everted, portion is thin. 

 The scapular extremity is lost, but there is some, though doubtful, evidence 

 of the possession of a small cleithrum, shown by a fragment of a small bone 

 apparently attached to it. The greater part of the interclavicle is present 

 in the specimen, lying on the under side of the procoracoid angle of the 

 scapular bone. The bone is flattened and expanded transversely, with a 

 short lateral projection on each side, and a thin but broad anterior margin. 

 In the middle, posteriorly, the bone is slightly thickened, but there was no 

 median, posterior elongation, as in the reptiles. The interclavicle is remark- 

 able for its small size, and thinness, as well as for the entire absence of 

 external pittings. As a whole, the clavicular, as well as the scapular girdle, 

 is markedly reptilian in character, far more so than in any other known 

 amphibian. 



"■Huvurus: The humerus resembles not a little that of Eryops, a figure 

 of which, more reduced, I have given for comparison, although a little more 

 slender, as are, indeed, all the bones of the extremities. The two expanded 

 extremities are twisted at an angle of about sixty degrees, the shaft between 

 them abruptly and much constricted, about 8 by 10 mm. in diameter. The 

 proximal anterior face is somewhat concave. The distal portion has a 

 large rounded radial convexity on its outer side, above which, _ separated 

 by a groove at the outer side, is a small process, evidently quite like that of 

 Eryops. The inner condyle is somewhat thickened; the entepicondylar 

 margin is convex from above downward, but wholly without an epicondylar 

 foramen, such as is present in the related genus Achelonia Cope.* 



*This opening has been shown to be accidental and not a foramen. — E. C. C. 



