140 Field Columbian Museum — Geology, Vol. II. ' 



the weight of the right arm lying across the body. The presternal 

 process extends about half an inch in front of the notarium. 



measurements of sternum. 



mm. 



Length in middle 88 



Greatest width, across attachments of first rib 80 



Length of rib margins 28 



Width at coracoidal articulations 40 



Length of presternal process in front of coracoids — 16 



Width of xiphisternal process 9 



Length of xiphisternal process 11 



Coraco- scapula. PI. XLIII, Fig. 6. This conjoined element is a mod- 

 erately stout, U-shaped bone, with the coracoid branch stouter and a little 

 longer than the scapular. The distal extremity of the scapula is slightly 

 expanded and flattened spatulate; the shaft is flattened and somewhat 

 constricted in width. There is a rounded protuberance on the outer or 

 upper margin, just beyond the glenoid rim, for the attachment of muscles. 

 This process appears to be wanting in the specimen previously described 

 by me of this genus, but it is possible its absence is due to some 

 postmortem compression. The glenoid articulation is deeply concave 

 from above downward, convex from side to side, and is bounded both 

 above and below by a prominent ridge, that on the inferior border being 

 much stronger than the upper one. The glenoid surface is placed 

 obliquely to the shaft of the bones, doubtless in life looking outward 

 and somewhat backward. The surface, from side to side, is narrower 

 below than above. A line indicating the sutural union of the two bones 

 passes directly through the middle of the articular surface transversely. 

 At the bottom of the U formed by the conjoined bones there is a 

 process, rather slender, arising from the inner surface of the scapula, 

 and reaching to the inner face of the coracoid, which it joins. It incloses 

 a small foramen between it and the coracoid, back of and below the 

 glenoid surface. A precisely similar process is found in the coraco- 

 scapula of Pteranodon, and in neither genus does the suture dividing the 

 coracoid from the scapula cross this process; it is, apparently without 

 doubt, either a separate ossification joined to the two bones, or else a 

 process from the scapula. I cannot at present examine the under sur- 

 face of this scapula, and have none of Pteranodon for comparison. In 

 Nyctosaurus, however, the process seems to be separated from the scapula 

 throughout a large part of its extent. If it really belongs with the scapula, 

 the inclosed foramen cannot be the usual supracoracoid foramen of the 

 reptilian coracoid. 



A similar foramen, though of larger size, is shown by Owen in the 

 coraco-scapula of Ornithocheirus sedgwicki (Paleontograph., 1857), which 



