MORPHOLOGICAL REVISION 135 



longer and stouter, and the zygapophyses a little better developed. Of the 

 caudals, save the two connected with the sacral vertebrae, only one small 

 block of matrix containing several more or less confused bones of the distal 

 part of the series is preserved. The chevrons are stout and short, united 

 above in a heavy hypocentral mass, which is excavated in its middle for 

 the notochord. In front of one of the preserved chevrons there is a pleuro- 

 centrum which seems to have separated the hypocentra ventrally. 



"The ribs are everywhere short. For the first nine or ten vertebrae 

 they are much dilated, both proximally and distally, with the distal portion 

 twisted somewhat from the plane of the proximal. They have a slight but 

 distinct curvature. In the region of the fifteenth vertebra the ribs are much 

 smaller, with the proximal portion less dilated, and with a longer, rounded 

 shaft. The first rib preserved in the matrix has its head closely applied to 

 the side of the second vertebra. The attachment of the ribs, at least anteri- 

 orly, was to both the transverse process of the neurocentrum and the pleuro- 

 centrum or hypocentrum, though no articular face is visible. The sacral rib 

 is quite like that of Eryops. It has a broad, stout, proximal portion artic- 

 ulating chiefly with the transverse process, but also below and in front with 

 the hypocentrum or region between the hypocentrum and pleurocentrum; 

 the distal part is much flattened and expanded, and is curved downward. 



^^ Pectoral girdle and extremity: Scapula-coracoid. The right side of the 

 pectoral girdle was found inclosed in the matrix close to the skull, lying on 

 the sides of the anterior vertebrae. The preserved parts are very complete. 

 Some fragments of the border of the coracoid, and the tip of the clavicle 

 only are missing. The united bone, on the whole, resembles that of Eryops, 

 save especially in the absence of the cleithrum, which is large and stout and 

 closely applied to the front border of the scapula in Eryops. The scapula 

 is much expanded above, and is flattened, a little thickened posteriorly, 

 the planes of its outer and inner surfaces directed a little inward anteriorly. 

 The scapula narrows rapidly to within a short distance of the glenoid fossa, 

 and then is widely expanded anteroposteriorly for the coracoids. That 

 portion corresponding to the procoracoid of the allied reptiles is a little 

 thickened, nearly flat, and directed somewhat toward the visceral side. The 

 lower anterior angle is nearly rectangular, and the mesial border of the whole 

 bone is gently convex in outline and is somewhat thinned. Posteriorly the 

 rather narrow coracoid projects strongly backward, its narrowed extremity 

 thickened and strongly curved toward the visceral side. The deep glenoid 

 cavity is directed upward, backward, and outward. Above, the thickened 

 hind border of the scapula divides, inclosing between its two branches a 

 rather deep, non-articular fossa. The anterior or external branch continues 

 downward in the same plane and direction as the scapular border, ending 

 in a subtriangular, articular facet looking backward and outward. The 

 end of the humerus lay in immediate apposition with this facet. The pos- 

 terior continuation of the scapular border, the thicker of the two, curves 

 inward and backward, in a strong, nearly semicircular sweep to near the 

 extremity of the coracoid. Between these two divergent borders there is 

 a deep cavity or fossa, evidently no part of the real glenoid fossa, pierced by 

 a large foramen or fenestra at its bottom. Just below the lesser ridge which 

 bounds this fossa posteriorly from the glenoid cavity, running from the 

 internal angle of the humeral facet upward and backward, and near its 

 middle part, there is a second foramen, which opens on the convex surface 



