ni 
= 
_A Skeleton of Great Fossil Beaver, Castorowdes Ohtoensis. 157 
the same in width, and about .25 of an inch in thickness. The 
scapula has a well-defined neck, which has a greater diameter of 
1.12 inches and a lesser of .62. A broad semicircular notch (very 
similar in form to that we see in Caséor), three-fourths of an inch 
deep, in the anterior border of the spine, throws the acromion proc- 
ess nearly an inch from the adjacent border of the glenoid 
cavity. 
The acromion, with the broader portion of the spine, presents a 
marked difference from the same feature in Castor. In the latter 
the spine is nearly the same thickness all along the crest, the 
acromion being twisted anteriorly. In Castoroides the acromion 
and spine are relatively much broader and flatter on the outer face, 
the former bending much more forward, and the latter narrowing 
much more rapidly upward and backward. 
The spine, in Castor, stands outward from the plane of the 
blade, at nearly right angles; in Castoroides, it slants at an angle of 
nearly forty degrees toward the axillary border, and away from the 
very broad, shallow sigmoid notch. ‘The anterior border of the 
blade diverges from the base line of the spine more rapidly than 
in Castor, giving a relatively wider area for the supra-spinatus 
muscle. 
The fossa for the infra-spinatus has about the same relative depth 
as in Castor. ‘The clavicle measures in a direct line, 4.36 inches ; 
following the curves, 5.25 inches. . 

Fic. 18.—One-third natural size. Clavicles: 1, of right side, outer aspect: 2, of left 
side; s, sternal end; a, acromial end. 
The longer diameter of the sternal enlargement isa full inch; the 
widest portion toward the acromial extremity is .87 of an inch. 
The sternal end is quite similar to what we see in Castor, but as we 
approach the middle of the bone, it is much more bent forward 
and downward, and thence more backward and upward, to the 
