180 Annals of the Carnegie Museum. 



THE RIBS. 

 (Plates XXXIII and XXXV). 



The ribs are remarkably well preserved, their symmetry and original 

 curvatures being in most cases retained. In the type nearly the entire 

 series is present, while the paratype has all of the right (fourteen) and 

 ten of the left side. 



The chief characteristics of the ribs in this species are the compara- 

 tively small curvature of the shafts and the low position of the tuber- 

 cular facet on the angle, which give an expanded position of the ribs 

 when in position, thus imparting breadth to the body. The costal 

 facet on the ventral end of the rib, when present, is enlarged, indicating 

 a strong attachment for the costal cartilage. The latter undoubtedly 

 was long. 



In Merycoidodon culbrrtsoni the shaft of the first rib is rod-like near 

 the angle, while in Fronierycochcvrns carrikeri it is flatter; it is notice- 

 ably heavy and rugose a,t the crest of the angle in the latter. The 

 first five ribs are flat and their antero-posterior diameter increases 

 gradually distad. The shafts of all the ribs back of the fifth are 

 more rounded, the last suddenly is shortened, has no tubercular facet, 

 and the curvature of the shaft is sinuous. 



the sternum. 



There are three sternebr?e belonging to the type (No. 1080) im- 

 bedded in the sandstone slab. These are heavy, flat, broad, and quite 

 deep, with rugose surfaces, indicating thick cartilaginoub attachments. 

 The presternum, if present, is buried in the slab underneath the main 

 mass of the skeleton. 



the fork limb. 



Although the fore limbs of the type are complete, the different 

 bones, especially of the forearm, were found so folded upon one another 

 that they cannot be studied in all of their details. In the following 

 description, therefore, use will be made of the paratypes as well as of 

 the type. 



The Scapula (Fig. 26). — \\'hen compared with Merycoidodon cul- 

 hertsoni the scapula of P. carrikeri is seen to have the suprascapular 

 border broader, imparling a more perfectly triangular outline to the 

 bone. One of the most noticeable features of the scapula is the median 



