446 Wortman — Studies of Eocene Mammalia in the 



90 



Figure 90. — Termi- 

 nal phalanx of fore- 

 foot of Sinopa agilis 

 Marsh ; three halves 

 natural size. (Type.) 



the 

 the 



the 



claws are compressed and pointed, figure 90, but at the same 

 time slightly fissured at their extremities. 



Although the magnum, trapezoid, and 

 centrale are missing, the distal articular 

 facets of the lunar render it certain that the 

 position of the centrale was entirely under 

 the scaphoid, as in Hycenodon. In this con- 

 nection, I wish to call attention to a speci- 

 men of Hycenodon in the present collection, 

 which agrees very closely with H crucians 

 of Leidy. A portion of the carpus is pre- 

 served, and it is of much interest to note 

 that the scaphoid, lunar, and centrale, figure 91, are coossified, 

 with the remains of the sutures still visible. This carpus dif- 

 fers from the one figured by Scott,* in that the lunar has a 

 91 large contact with 



the unciform, and 

 the centrale lies 

 wholly upon 

 radial side of 

 lunar, under 

 scaphoid. 



Of the pelvic 

 girdle, the ilium is 

 considerably expanded, and has a strong downward and outward 

 curvature, as in Hycenodon • the peduncle is short and the 

 tubercle for the rectus is large and rugose. The ischium is 

 elongate and slightly expanded at its distal end. The pubis is 

 not preserved. 



The femur has a strong resemblance to that of Hycenodon / 

 the hemispherical head is supported by a moderately short, 

 stout neck ; the fovea is distinct, the digital fossa deep, and the 

 major trochanter rises almost to a level with the head ; the 

 trochanter minor is large, and the third trochanter is distinct 

 and placed at a- considerable distance down the shaft. The 

 distal end of the bone exhibits the characteristic thickening of 

 the lower end of the shaft, just before joining the condyles, as 

 well as the general clumsy appearance seen in Hycenodon. 

 The patella is relatively small, elongate, and narrow. The 

 tibia, figures 92-93, is also markedly Hysenodont in character. 

 The cnemial crest extends more than half-way down the shaft ; 

 the internal malleolus is large, and the trochlea is little grooved. 

 The fibula is not so much reduced as it is in Hyamodon, but, 

 as in that genus, there is a large contact with the calcaneum. 

 The calcaneum, figure 94, has a moderately elongated tuber, 

 and very convex astragalar and concave sustentacular facets. 



* Jour. Acad. Nat. Sci., Phila., 1886. 



Figure 91. — Coossified scaphoid, lunar, and cen- 

 trale, of Hycenodon crucians Leidy ; natural size, 

 a, top view ; b, front view ; c, inner view. 



