THE OSTEOLOGY OF VULPES MACROTIS. 409 



shallow bicipital groove, is the greater tuberosity, it being broad, flattened from 

 without inward, and having its thick, roughened, convex margin reared well above 

 the general summit of the bone. Distally, at the other end of the humerus, the 

 articular trochlea? are conspicuously developed, being distinctly separated from each 

 other by an intertrochlear groove, which is especially deep posteriorly. The radial 

 condyle is small and pitted upon the outer aspect, while the ulnar or internal con- 

 dyle is more prominent, has a very sharp and raised inner boundary, and develops 

 a tuberosity instead of a pit upon its outer side. The deep anconeal fossa is per- 

 forated by a large intercondylar foramen, and the supinator ridge, extending up the 

 shaft from the external condyle is strongly marked. Another strong muscular 

 ridge passes entirely down the shaft from the greater tuberosity to the internal 

 condyle, it, at the lower end of the bone, being spirally parallel to the aforesaid 

 supinator ridge. Between the two extremities, or the middle third of the shaft of 

 the humerus, is otherwise smooth and subcylindrical in form; the shaft as a whole 

 exhibiting a gentle sigmoid curve from one end to the other. Its deltoid ridge, 

 occurring in the upper third of the shaft in the muscular line described above as 

 passing down from the greater tuberosity, is but feebly pronounced, being not nearly 

 as well marked as it is in some of the other carnivora, as for example in the Ursidse. 



In common with all other mammals the forearm or anti-brachium has in its 

 skeleton the two bones radius and ulna, both articulating with the humerus at 

 their proximal extremities and with the upper row of the carpus, distally. Between 

 the bones themselves the articulation is very close, both at their extremities and by 

 elongated roughened facettes, one on either bone, at the junction of upper and 

 middle thirds. Here a dense ligament helps to hold the bones together. As we 

 have seen, the radius, although shorter than its companion, is much the stouter 

 bone of the two, its antero-posteriorly flattened shaft is but very slightly bowed, 

 and nearly of uniform calibre from one end to the other. Its extremities are en- 

 larged for the articulatory purposes, as has already been stated. The facet for the 

 humerus is of an oblong shape, and is co-extensive with the greater sigmoid cavity 

 of the ulna. Distally, the carpal facet of the radius is much larger, also oblong in 

 outline and concave. Here, anteriorly, on either hand occurs a deep, short groove, 

 which in life transmits tendons. Flower says that the radius in the carnivora 

 " differs from that of man, inasmuch as its upper end is broad, flattened and extends 

 further across the front of the humeral articular surface, forming part of the hinge ; 

 and although it is never ankylosed with the ulna, scarcely any appreciable amount 

 of movement is allowed between them." 7 



At the distal extremity of the antibrachium, the ulna is about equal in length 

 to the radius, its end being considerably enlarged, projecting and mesially concaved 

 in conformity with the radius in such a way as to complete the concavity in which 

 the proximal row of carpal bones articulate. This distal ulnar enlargement is less 

 than one-third of that of the radius at the same extremity. Proximally, the ulna 

 projects over a centimeter and a half beyond the radius, the projection being the 



7 Loc. cit., p. 274. 

 52 JOURN. A. N. S. PHILA., VOL. XI. 



