GLIRES OF THE SANTA CRUZ BEDS. 437 



cervical vertebrae are relatively somewhat heavier than in Viscaccia and 

 the axis has a broader spine ; in the trunk the anterior thoracic vertebrae 

 are larger and the lumbars smaller; evidently the back was not so 

 strongly arched as in the recent genus, for there is no such disproportion 

 in the relative length of the fore and hind limbs as characterizes the latter, 

 the fore limbs being longer and heavier and the hind limbs shorter and 

 more slender proportionally. 



The scapula has a slender neck and a rather broad, triangular blade, 

 which, so far as can be determined, is not unlike that of Viscaccia in 

 shape. The humerus, the proximal end of which has not been found, 

 resembles that of the modern genus, but the deltoid crest is even more 

 prominent and rises more abruptly from the shaft ; the distal end is 

 narrower and the internal epicondyle is less prominent ; there is no epi- 

 condylar foramen, but a large supratrochlear perforation, and the supinator 

 ridge is but feebly developed ; the trochlea, which is rather narrow, has a 

 prominent internal flange for the ulna and three facets for the radius, a 

 median convexity, with slightly concave surfaces on each side of it. 



The fore-arm bones are slender and elongate, with decided forward 

 curvature. The ulna, no specimen of which with complete olecranon has 

 yet been found, has a prominent coronoid process and anteriorly has only 

 a narrow facet for the humeral trochlea, nearly the whole width of which 

 is occupied by the radius ; the shaft is slender, laterally compressed and, 

 on the outer side, is conspicuously channelled for most of its length, and 

 the distal end is contracted to a narrow, convex facet for the pyramidal. 

 The radius has a broad proximal end, with three facets for those on the 

 humeral trochlea ; the shaft, which proximally is of a transversely oval 

 section, for most of its length is of subtrihedral shape, much as in yiscac- 

 cia ; the distal end is unknown. Of the manus only metacarpal V has 

 been found ; this is very small, though relatively larger than in the recent 

 genus, and is of similar shape, except that the distal end is less expanded. 



The only known example of the femur has lost the proximal epiphysis 

 and is otherwise damaged, but its length may be determined with sufficient 

 accuracy to show that its proportions were very different from those of the 

 femur of Viscaccia, being relatively much shorter and more slender. The 

 small patella is of nearly uniform width ; proximally it is quite thick, thin- 

 ning nearly to an edge at the distal end ; the surface for the femoral 

 trochlea is decidedly convex transversely, very slightly concave longitudi- 



