AFFINITIES OF .^LUROPUS MELANOLEUCUS. 169 



addition to its supoi-ior relative length, tliis l)one is specially distinguished by the compai-a- 

 tive narrowness of the distal extremity and the shar]) point formed by the preaxial 

 malleolus. In ^Inropus, on the other hand, tlie distal extremity of the radius (W. 20. 

 tig. 8) is much more expanded above the articuh^r surface, and the preaxial malleolus 

 does not descend to nearly the same degree. Consequently the profile of this extremity is 

 quite different from that of the corresponding bone in Ursns ; while (as may be seen from 

 the figures) there arc equally important differences in the contour of the distal articular 

 surfaces of the two bones. In all the aliove respects the radius of ^Eliirus (PI. 20. fig. (5) 

 is es.sentially similar to tiiat oWEZ/iroii/is. Although differing to a considerable degree, 

 the radius of Proci/oii comes nearer to the type of the two latter genera. 



Passing on to the manus (PI. 20. fig. 8 ), the most noticeable feature in ^l^luropm is 

 the development of a very large preaxial extra-carpal (r.s.) in addition to the ordinary ulnar 

 sesamoid, or pisiform [pi). The former is wedged in between the scaphoid process of the 

 scaplio-lunar and the first metacarpal, so as to articulate largely witli Ixjtli bones. A 

 precisely similar arrangement obtains in ^EIki'ks, alihough the radial extra-carpal is of 

 very considerably smaller dimensions in that genus. (_)n the other hand, in the carpus of 

 Vrsus the radial extra-carpal * is reduced to a small nodule of bone articulating exclu- 

 sively with the scaphn-lunar. In the Raccoons, if such a preaxial bone is developed at 

 all, it must likewise be very minute. The huge size of this bone in ^Ehiropus, which 

 simulates a sixth metacarpal, is unique. 



Both in ^ISluropm and ^Elnrns the metacarpals are relatively short, this abbreviation 

 being carried to tbe greatest extent in the former. In regard to this feature Froci/on 

 departs further from the type of the two genera under consideration than does I'rsns. 

 Einally, it may be mentioned that the terminal phalanges of ^Elnropns (PI. 20. fig. 12) 

 and ^'Elnrus differ from one another only in point of size, but are quite unlike the corre- 

 sponding bones of both Proci/ou and Urs/is. Tlieir most striking common features are 

 their shortness, widtii, and thinness, coupled with the great relative development of the 

 basal protecting sheath. 



The femur of ^Eluropus (PL 20. fig. !)) is characterized by its shortness and flatness, as 

 well as by the small antero-posterior extent and nearly symmetrical lorm of the trochlear 

 surface for the patella. On the posterior aspect (fig. !) a) the digital fossa is very deep, and 

 the area between tlu> head and the two trochanters remarkable for its width and flatness. 

 Owing to this, the two trochanters are widely separated from one another. Another 

 feature is the relatively small size of the lesser trochanter, which is situated on the pre- 

 axial bordei- of the shaft, so as to be largely visible in a front view. Although its shaft 

 is proportionally longer and more slender, the femur of ^Eltiriis presents tJie essential 

 features of the corresponding bone of ^Eluroptis ; and in the femur oiProci/on, owin"' to 

 relatively greater shortness and width, the resemblances to the latter are even more 

 strongly marked, although less is seen of the lesser trochanter in a front \iew. On the 

 other hand, the Ursine femur (PL 20. fig. 10) is totally unlike that of the genus undt^r 

 consideration. Not only is the shalt much longer and more nearly cylindrical, but the 

 ti'ochlear surface for the patella is more elongated, and has one lateral border C')nsideral)lv 



* See Flower, 'Osteology of the Manniialia,' i>. 2^7, fig. 93 (1SS3). 



