HAPLODONTIDiE— LIMB BONES OF HAPLODON RUFUS. 581 



and pubic rami enclose a very large obturator foramen, of subtriangular shape, 

 but with all the corners rounded off. Tlie '•horizontal'' and "descending", 

 in this case nearly anterior and posterior, rami of the pubis, are about equally 

 slender, notably more so than the ischium ; the descending ramus is at a right 

 angle with the ischium. There is a well-developed tuberosity of the ischium, 

 but no notch in the bone above it. The pubic symphysis is short, and the 

 connection of the bones slight. 



Bones of the hind limb. — The femur is a stout straight bone about two 

 inches long, the shaft much flattened, the distinction of parts at either extrem- 

 ity well marked. The globular head represents more than a hemisphere; it 

 stands off from the shaft at an angle of about 45°, upon a constricted but 

 short neck. It bears a well-marked pit, denoting the insertion of the liga- 

 mentum teres. The trochanter major is very prominent, rising as high as the 

 head of the bone, a deep notch intervening; there is a conspicuous fossa on 

 its posterior face, while from its outer aspect a prominent "glutaeal" ridge 

 runs nearly half way down the shaft of the bone, like the corresponding 

 "deltoid" ridge of the humerus. There is a strongly marked lesser trochanter — 

 a tubercle on the postero-internal aspect of the shaft, just below the neck of 

 the bone, prolonged downward as a sharp ridge. No third trochanter is 

 recognizable. The condyles are well formed; the inner is larger than the 

 outer, reaching farther down, especially farther back, and being decidedly 

 thicker across; its articular surface is, however, narrower. Behind, the con- 

 dyles are separated by a deep notch ; in front, a trochlear surface (broad 

 groove) for the play of the patella reaches far above the portion of the joint 

 which enters into the tibial articulation proper. 



There is a large sesamoid bone in the knee-joint, the patella being one- 

 third of an inch long, of conico-triangular shape, with smooth concavo-con- 

 vex posterior face for articulation with the femoral trochlear groove which 

 surmounts the condyles in front. 



Of the t\vo bones of the cms, the tibia alone enters into the construction 

 of the knee-joint, the head of the fibula being much below the articulation. 

 The tibia, as long as the femur or slightly exceeding it in length, is straight 

 when viewed from the front, but from the side shows a decided /-shape, 

 having an anterior convexity above and corresponding posterior bend below. 

 The lower half of the shaft is smooth and cylindrical, but the upper develops 

 two large crests, one anterior, like the "spine" of the human shin-bone, the 



