98 AMERICAN PERMIAN VERTEBRATES 



examined; and there is no trace of cleithrum in any of the speci- 

 mens examined. 



The upper end of the scapula is moderately expanded in nearly 

 a plane, its upper margin very slightly convex, and squarely 

 truncated, as though for a cartilaginous suprascapula; this border 

 is about three millimeters in thickness. The posterior margin 

 is thickened and rounded, and nearly straight for fully one-half 

 the length of the conjoined bone. The anterior border is thickened 

 moderately on the upper fourth, thinned and irregular in outline 

 for the remainder of its border. The inner surface above is gently 

 convex antero-posteriorly, convex on the corresponding outer 

 surface. Below, the posterior border turns a little backward 

 and outward to end in the preglenoid tuberosity. On the inner 

 surface a thickening begins below the middle posteriorly, turning 

 backward in a broad sweep to terminate in the cartilaginous 

 border for the coracoid or metacoracoid. Between these two 

 borders the surface for the most part is convex, and has no fossa or 

 foramen as in the other reptiles and the amphibians. The upper 

 part of the glenoid fossa is shallow. At some distance above the 

 preglenoid tuberosity and back of the middle of the outer surface 

 there is a small foramen piercing the bone; this is the usual supra- 

 glenoid foramen, as I have called it, but situated unusually far 

 forward and in front of the border; its position in Dimetrodon is 

 very near to this border, while in scapulae which I have referred 

 to Ophiacodon (see anted) this foramen pierces the supraglenoid 

 fossa, as in the Cotylosauria and amphibians. The scapula-coraeoid 

 suture runs almost straight from a little above the middle of the 

 coracoid border, through the middle of the preglenoid tuberosity 

 or facet to the angle immediately above the anterior emargination 

 of the so-called procoracoid. The suture is clearly indicated in 

 various specimens, and in one the two bones are separated. The 

 lower part of the scapula turns inward, so that the coracoid as a 

 whole is nearly horizontal. This latter bone is much wider behind 

 and is thin throughout the most of its extent, its inner border 

 lying by the side of the interclavicle, thinned throughout most of 

 its extent and for the most part nearly straight; the front border 

 is also thin, with a subangular protuberance and a deep angular 



