540 ANATOMY OF VERTEBRATES. 



the lunare, which completes the wrist-ball ; at its distal surface it 

 joins the ' intermedium,' the trapezium, and the trapezial sesamoid : 

 the cuneiform offers a cup for the hemispheric end of the styloid 

 process of the ulna and a flatter surface for the pisiform ; this 

 wrist-bone is long, and its articular surface is divided between the 

 ulnar process and the cuneiform. The intermedium and cunei- 

 form combine to form the cup for the ball common to the magnum 

 and unciform, of which the latter bone contributes the larger 

 share. The intermedium articulates with the trapezoid. The 

 distal series of carpal bones have the usual relations to the 

 metacarpals. The first, second, fifth, and fourth metacarpals, 57, 

 progressively increase in length, with similar proportions as to 

 thickness ; but the middle metacarpal is double the length of the 

 second, and suddenly contracts into a shaft more slender by half 

 than the contiguous metacarpals. The phalanges of the same 

 digit. III., are filamentary, and support the hooked probe-like finger 

 adapted for the extraction of the xylophagous larvas — the favourite 

 food of the Aye-aye — from the canal in the Avood which has been 

 exposed by the scalpriform incisors. 



The ilium, 62, is long and narrow, slightly expanded at both 

 ends : it articulates with the two first sacral vertebrrs, just touching 

 the second by a projection above its middle. The iliac bones 

 incline to the acetabula at an angle of 140° with the lumbo- 

 sacral axis. There is an elongate tuberosity above the acetabu- 

 lum for the origin of the rectus femoris. The ischia, 63, are 

 continued almost in a line mth the ilia, the posterior contour 

 describing a very feeble curve concave backward ; the tuberosities 

 are slightly everted : a small projection behind the lower part of 

 the acetabulum divides the great from the small ischiadic notches, 

 both of which are very shallow. The obturator vacuities are 

 large. The pubic oones, 64, pass from the acetabula at almost a 

 right angle mth the ilio- ischial axis ; they converge to a short 

 symphysis. There is a slightly marked ilio-pectineal promi- 

 nence. The femur, 65, has a straight shaft, one third longer 

 than that of the humerus. The neck is short: the great tro- 

 chanter rises to the height of the head, and at the outer and 

 lower part is developed into a small tubercle. Opposite to this 

 the lesser trochanter projects from the inner side to a greater de- 

 gree. The orifice for the medullary artery is at the back part, one 

 fourth of the length from the head ; the canal ascends. The inner 

 condyle is rather the larger. The outer border of the rotular 

 groove projects most. There is a sesamoid bone ( ' fabella ' ) in 

 each origin of the gastrocnemius. The tibia, 66, is about two 



