MONOCLONIUS CKASSUS. 



79 



Fig. 85. — A, External view of right humerus of Monoclonius 

 crassus Cope, No. 3998, American Museum of Natural 

 History; B, posterior view of same, h, Head; d, deltoid 

 ridge. One-eighth natural size. 



section throughout most of its length, becoming somewhat triangular toward its distal 

 extremity. It is directed downward and backward, but distally it curves inward and slightly 

 forward in such manner as to bring the inner surface 

 of the extremities of the ischia in contact for a con- 

 siderable distance. It is evident, however, that the 

 union between the ischia was only cartilaginous. In 

 fig. 83 there is given a side view of this imperfect 

 ischium. Unfortunately the draftsman has made 

 no attempt to eliminate the distortion in the bone 

 due to crushing. 



The scapula. — There is a right scapula and cora- 

 coid, nearly complete, which may be referred to the 



present genus and species. 



The glenoid cavity is almost 



exactly bisected by the scap- 



ulo-coracoid suture, though 



from foreshortening this does 



not appear to be the case in 



the accompanying figure (fig. 



84) . The external surface of 



these bones is regularly but 



gently convex longitudinally; 



the inner surface is concave. 



The anterior margin of the 



coracoid is convex, with the inferior angle produced into an acute angular 



process, bent backward and inward. Between this process and the lower 



border of the glenoid cavity there 



is a deep notch or emargination of 



the inferior or posterior border of 



the coracoid. The external open- 

 ing of the foramen is midway be- 

 tween the anterior and posterior 



borders of the coracoid and directly 



opposite the point where the 



coraco-scapular suture joins the 



surface of the glenoid cavity. In- 

 ternally the foramen opens at the 



coraco-scapular suture. In gen- 

 eral the external surface of the 



coracoid is regularly convex, while 



the internal is concave. The scap- 

 ula is comparatively stout and heavy toward its lower 

 extremity, but thin, flat, and somewhat expanded at its 

 upper extremity. On the external inferior margin a 

 rugose surface extends for some distance above the 

 glenoid cavity and probably served as a surface for the 

 attachment of the long abductor or deltoid muscle. 

 From this rugosity a prominent ridge extends upward 

 obliquely across the external surface of the scapula to its 

 anterior margin. 



-The limbs.— Of the bones of the fore limbs I find in the collection only a right humerus. 

 It was doubtless upon the evidence afforded by tins bone that Cope based his remark that the 

 fore limbs were robust. Proximally the humerus is much expanded transversely, the deltoid 

 ridge being continuous throughout about one-half the length of the bone and turning back- 



Fig. 86. — Anterior view of right 

 femur of Monoclonius cras- 

 sus Cope, No. 3998? Ameri- 

 can Museum of Natural His- 

 tory, h, Head; t, great 

 trochanter; c, internal con- 

 dyle. One-eighth natural 

 size. 



D 



Fig. 87.— A, Posterior view of tibia of Monoclonius 

 crassus Cope, No. 3998, American Museum of 

 Natural History; B, lateral view of same, 

 much distorted by crushing, as, Astragalus. 

 One-eighth natural size. 



