MERYCOIDODON 53 



smaller species, O. gracilis, . . . Mc. I is proportionally longer and stronger than in O. culbertsoni. The proximal 

 end bears a small head for the trapezium, and the distal end is also rounded and keeled on the palmar side. . . . 

 The proximal end of Mc. II possesses on the ulnar side an articular surface for the magnum, and Mc. Ill is 

 excluded thereby from a contact with the magnum. . . . The proximal surface of Mc. II, which is considerably 

 greater than the lateral, is taken up entirely by the trapezoid. This arrangement is obviously a preliminary for 

 that found in Merychyus and Merycochcerus, in which Mc. Ill has developed a facet for the trapezoid and 

 Mc. II is excluded from union with the magnum. On the ulnar side of Mc. II (in Orcodon) there is a hollow 

 into which a projection from Mc. Ill is dovetailed. Mcs. Ill and IV are symmetrical and of nearly equal 

 strength; Mc. Ill is indeed longer, but the distal ends of both are in the same transverse plane. . . . Mcs. Ill 

 and IV are very well matched, and Mc. IV is surpassed by a strong projection of Mc. III. . . . Mc. V is shorter 

 and slimmer than Mc. II. . . . 



The phalanges of the first row arc very long, . . . resembling those of some of the carnivores in that they 

 are long, slender, and bowed upward. The proximal end is deeply concave, and the posterior border is incised 

 for the keel of the metacarpalia. The phalanges of the second row are also fairly long; the distal articular roller 

 is bowed far around on the dorsal side and is asymmetrically developed in that the outer margin is higher than the 

 inner and the roll at the same time is obliquely placed. In consequence of this arrangement the terminal 

 phalanges show a definite degree of convergence. . . . The terminal phalanges . . . are almost symmetrical in 

 that the inner border is only slightly shorter and straighter than the external; the palmar side is very flat, the 

 dorsal side, however, is strongly arched, and the free end is fairly blunt. . . . 



In the pelvis . . . the ilium and ischium are in the same line and of about equal length. The ilium has a 

 very long, slender, compressed part, which suddenly expands anteriorly into a large plate, fairly similar to the 

 corresponding part in many of the carnivores, but it is proportionally wider and has no excavated gluteal sur- 

 face; it lies in nearly the same plane as the strangulated neck and is turned outward but slightly. . . . The 

 anterior border of the plate is rounded, but it forms an acute angle with the lower border, which is entirely 

 different from the gradual transition present in the carnivores. . . . 



The ischium is long and very flat; the ischial tuberosities are not so large as in recent artiodactyls. The 

 pubis is short and strong; the pubic symphysis is short; that of the ischium, on the contrary, is fairly long. The 

 acetabulum is a very long, slender obovoid. . . . 



.... The head of the femur is distinctly set off by a constriction from the rest of the bone; the external 

 trochanter is massive, but it does not rise higher than the head, and the trochanteric fossa is very deep. . . . The 

 internal trochanter is large and pointed and is well developed. . . . Between the head and this process there is a 

 ridge. . . . The shaft is proportionally short, strong, and almost round in cross section. The distal end is very 

 massive; the trochlea for the patella is wide and symmetrically developed. . . . The patella is wide and flat, 

 with rounded upper margin and pointed lower margin. 



The tibia is proportionally very short, even shorter than the femur. . . . The median projection of the 

 proximal articular surface is low; the two facets are weakly convex fore and aft and are of nearly equal size; 

 the anterior crista projects strongly and has a long course downward ; the upper end of the crista is especially 

 massively built and is offset by a conspicuous constriction from the external articular surface. The shaft is strong 

 and ... is three-cornered above and compressed fore and aft below. The edge turned toward the fibula is an 

 obliquely placed ridge, feebly developed; the inner edge, however, is more rounded. The distal end shows . . . 

 that the inner knuckle is long and somewhat pointed. Of the articular surfaces for the astragalus, the outer is 

 wider and the inner deeper, with a median projection between these two facets. . . . The tibia . . . combines, 

 like so many other skeletal parts, characteristics which were present but are now separated in the ruminants and 

 swine. The fibula is complete and shows no tendency to fuse with the tibia. . . . 



The foot is more reduced than the hand, and, what is of especial interest, although the hand is in position 

 to reduce itself adaptively, as it truly does in later genera of the family, the foot still remains (with one single 

 exception) strongly inadaptive. 



The astragalus is wide and low . . . ; the trochlear condyle for the tibia is asymmetrical, with the outer part 

 much larger and more prominent than the inner which extends far downward and is separated from the scaphoid 

 facet simply by a small projection. . . . On the external side of the astragalus there is a broad surface for the 

 external knuckle. The lower facet for the calcaneum is large and simple and is delimited on its tibial margin 

 by a ridge. . . . The facet for the scaphoid is very large and that for the cuboid fairly small. . . . The calcaneum 

 is long, strong, and laterally compressed, with rounded borders; the free end is thickened and shows on the 

 posterior side a deep conduit for the tendon of Achilles; the articular surface for the fibula is long and slightly 

 bowed fore and aft; the anterior border is not abruptly truncated. . . . The distal end is wide, and its anterior 

 border is not pointed. . . . The dorsal and plantar borders of the calcaneum are closely parallel. The distal end 

 is transversely widened, and the contact surface with the cuboid is large. . . . The astragalus lies more on the 



