GLIRES OF THE SANTA CRUZ BEDS. 467 



men is of more irregularly quadrate, less oval form. The pubis is quite 

 elongate, thin and laterally compressed ; it forms a long symphysis with 

 its fellow of the opposite side. 



There is much more disparity between the lengths of the fore and hind 

 limbs than in any existing member of the family. 



The humerus (Plate LXIX, fig. 4) is very short and slender, but, except 

 in size, has a close resemblance to that of Dolichotis ; the tuberosities are 

 reduced, the external one not rising above the level of the head, but is 

 quite broad transversely ; the shaft is slender and the deltoid ridge is but 

 weakly developed. The distal end is narrow and the epicondyles nearly 

 obsolete ; there is no epicondylar foramen ; the trochlea, the whole breadth 

 of which is occupied by the radius, has the usual division into three parts, 

 of which the median convexity is more prominent than in the recent 

 genus ; the anconeal and supratrochlear fossae are deep and connected by 

 a perforation. 



No difference between Rocardia and Dolichotis is more striking than 

 the great elongation of the fore-arm in the latter and its shortness in the 

 former ; instead of far exceeding the humerus in length, as it does in the 

 modern genus, it is considerably shorter, so that the segments of the fore 

 limb have more the proportions seen in Cavia. 



The radius (Plate LXIX, fig. 5) is very slender; the proximal end is 

 broad, occupying the whole humeral trochlea, with which it is so inter- 

 locked as entirely to prevent any movement of rotation. The shaft, which 

 js antero-posteriorly compressed, is less strongly arched forward than in 

 Cama, and the distal end is but moderately expanded and has a shallow 

 tendinal sulcus on the anterior side. 



The ulna, though far shorter, is much stouter than in Dolichotis and 

 has a shorter olecranon ; the sigmoid notch is deep, describing more than 

 a semicircle, and the shaft is as stout as that of the radius, quite as thick 

 as in Cavia, but less curved ; the distal end bears a narrow, convex facet 

 for the pyramidal. 



Of the manus (Plate LXIX, fig. 6) only the metacarpus and a few 

 phalanges are known, but these suffice to show that it was very small. 

 Almost certainly the number of digits is four. The functional metacarpals 

 have the same arrangement as in the recent members of the family in two 

 symmetrical pairs. Metacarpal II is short and slender, moderately ex- 

 panded at the proximal end ; as in Dolichotis, it has three carpal facets, 



