410 THE OSTEOLOGY OF VULPES MACROTIS. 



olecranon or anconeal process, — the most conspicuous part of this, bone of the fore- 

 arm. It is strong, quadrilateral in outline, compressed from side to side. A deep, 

 longitudinal notch is found on the supero-anterior angle of the olecranon. While 

 its postero-internal aspect is somewhat concaved, caused by a prominent raised rim 

 of the edges of the process, proximally and below. The sigmoid cavity is deeply 

 sculpt, and its supero-anterior angle in some positions of the humerus will pass into 

 the intercondylar foramen of that bone. 



For rather more than its superior third the shaft of the ulna is obliquely 

 flattened, so that its anterior surface looks forward and Outward. It gradually 

 contracts as it approaches the above-described articulation with the radius in the 

 narrow " interosseous space." Below this point the shaft of the ulna is very slender 

 and straight, and exhibits upon its inner aspect a fine, deep, longitudinal groove, 

 which runs nearly to its distal end. Among all the carnivora we meet with this large 

 compressed olecranon on the ulna, and observe that its shaft tapers gradually from 

 above downward in the direction of the wrist. 



In the mantis we have the carpus, metacarpus and phalanges. According to 

 Flower, " In the carnivora, the scaphoid and lunar bones always coalesce into a 

 single scapho-lunar [as in Ursus americanus~\, with which the centrale is united, the 

 latter never appearing 8 as a distinct bone, except sometimes in very young animals. 

 The radial accessory ossicle or sesamoid is generally present. All have five digits, 

 with the complete complement of phalanges, except the Hy<zna, in which genus 

 the pollex is represented only by a rudimentary metacarpal. This digit is usually 

 much reduced in size, and often, as in the dog, does not reach the ground in walking. 

 It is best developed in the bears and allied forms. The first metacarpal is never 

 more freely movable than any of the others. As a general rule the middle digit is 

 somewhat the longest, the second and fourth nearly equal to it, the fifth shorter, 

 and the first the shortest. 



" As the toes are nearly always armed with long, strong, curved, and sharp 

 claws, the ungual phalanges are large, strongly compressed, and pointed, and they 

 develop from their base a broad, thin lamina of bone, which is reflected over the 

 root of the horny claw, and holds it more firmly in place." 9 



In Vulpes macrotis the radial accessory ossicle of the carpus is very small and 

 rudimentary, while the pisiform on the ulnar side of the wrist is powerfully 

 developed, and articulates with a distinct facet upon the outer side of the cunei- 

 form. This latter bonelet, together with scapho-lunar, forms the convex proximal 

 facet for articulation with the radius and ulna of the antibrachium, the last named 

 affording about four-fifths of the surface, and articulating entirely with* the radius. 

 For the distal row we have four carpal bones, the largest of which is the unciform, 

 which articulates with the proximal ends of the fourth and fifth metacarpals — the 

 first, second and third metacarpals each having a small bone to itself. Of these 



8 B. G. Wilder, " On the Composition of the Carpus in Dogs." Bull. Cornell University, Vol. 

 I, p. 301, 1874. 



9 Osteology of the Mammalia, pp. 287-289. 



