158 Cincinnati Society of Natural History. 
acromion. ‘The deep, roughened cavity for the attachment of the 
muscle which reaches from the coracoid process is a marked 
feature. 

Fic. 19.—One-third natural size. 1, humerus of right side. 2, left fumlenns, epi- 
physis wanting at proximal end. s, Supinator ridge; 0, outer condyle; 7, inner con- 
dyle; g, greater’ tuberosity; J, lesser tuberosity: ¢, third tuberosity; 6, bicipital 
groove; of, olecranon fossa. 
In the study of the humerus the marked resemblance to its 
homologue in Castor is evident; its length, 7.36 inches; greatest 
breadth (across condyles), 2.25 inches ; breadth at upper extremity, 
2.12 inches; diameter of shaft, including deltoid ridge with its 
tuberosity, 1.9 inches. 
Looking at the entire bone, it is flattened, and has quite a twisted 
appearance, seen from the outer border, owing to the broad blade 
of the supinator ridge. This blade extends from the outer con- 
dyle upward, forward and inward, nearly fading out about two- 
thirds of the way, and almost connects with a low ridge downward 
from the lesser tuberosity. The head is sharply defined. With the 
shaft in a vertical position, the head looks backward more than 
upward. It is very convex in all directions. The articulating 
surface antero-posteriorly is relatively longer than in Castor. Lat- 
erally and posteriorly there is a short but well-defined neck. 
The greater or outer tuberosity is less prominent than the inner, 
but much more massive, and each is separated from the head by a 
well-marked groove; the outer groove, the bicipital, is wide 
enough to admit the last joint of a man’s little finger edgewise, and 
the inner sufficiently to admit the same flatwise. ‘This greater 

