485 THE RABBIT chap. 



surface being grooved for the firmer attachment of the horny 

 claw. Small sesamoid bones are situated on the under or 

 palmar side of the joints of the digits. 



The ends of the long bones in lioth limbs are separately ossified as 

 epiphyses (compare p. 480), which eventually unite with the shaft of the 

 bone in question. 



The pelvic arch consists of two lateral halves or innominate 

 hones, the long axis of which is almost parallel with that of 

 the vertebral column (Fig. 121), and which are firmly united 

 anteriorly and internally with the transverse processes of the 

 sacral vertebrae by a rough surface, while ventrally they are 

 connected together by cartilage at the pelvic symphysis. On 

 the outer surface of each innominate bone, at about the 

 middle of its length, is a deeply concave cup, the acetabulum, 

 for articulation with the head of the femur : in it, in young 

 rabbits, a triradiate suture can be seen, marking the 

 boundaries of the three bones of which the innominate is 

 composed (p. 50). Of these, the antero-dorsal is the ilium, 

 which is connected with the sacrum. The postero-ventral 

 portion of the innominate is perforated by a large aperture — 

 the obturator- foramen, through which a nerve of that name 

 passes, the bone above and behind it being the ischium, and 

 that below it the pubis. Behind the obturator foramen the 

 ischium has a thickened posterior edge or tuberosity, and 

 then curves round and becomes continuous with the pubis, 

 both bones taking part in the symphysis. 



In young rabbits it will be noticed that the part of the pubis which 

 enters the acetabulum consists of a small, distinct epiphysis. 



The hind-limb has undergone rotation forwards (Fig. 121), so as to 

 be brought, like the fore-limb, into a plane parallel with the median 

 vertical plane of the body ; but the rotation being forwards, and the 

 bones of the shank not being crossed, the preaxial border is internal 

 in the whole limb, and the original dorsal surface looks, on the whole, 

 forwards. 



