SKELETON OF QUADRUMANA. 541 



lines shorter than the femur, and soon contracts below the head 

 to a compressed shaft, giving a long and narrow subelliptic section ; 

 at the upper half it is very slightly bent, with the convexity 

 forward. A roughish surface is continued from the tuberosity 

 nearly one third of the way down the fore and outer part of the 

 shaft. The orifice of the medullary canal is one fourth of the way 

 down, just within the posterior border ; the canal slopes downward. 

 The tibials one fifth longer than the ulna. The fibula, 67, touches 

 the tibia only by the two extremities articulating mth that bone, 

 lea\ang an interosseous space co-extensive with their shafts. The 

 outer malleolus is shorter and thicker than the inner one. There 

 is a sesamoid in the external lateral ligament of the knee-joint, at 

 its insertion into the head of the fibula. 



The tarsal bones, 68, are seven in number. The naviculare has 

 its shallow concavity for the astragalus supplemented by the 

 strong ligament arising from its posterior and inferior margin, and 

 inserted into the fore part of the inner malleolus ; anteriorly it 

 articulates with the three cuneiform bones, and externally at its 

 fore part with the os cuboides: its depth exceeds its leno-th. 

 The calcaneum offers two articular surfaces to the astragalus, 

 rather far apart ; the lever projects moderately beyond the hinder 

 surface, and is curved a little upward and inward. The ento- 

 cuneiform offers at the anterior half of its outer part a trochlear 

 surface, concave in one direction, convex in the opposite, to 

 the powerful hallux. The meso- and ecto-cuneiform bones are 

 narrower, the outer one is of nearly equal length with the inner, 

 the middle one being the shortest. The cuboid is large and 

 long, with the lower half of its calcaneal surface convex, the 

 upper half concave, for an interlocking joint with that bone; 

 it is grooved externally and beneath for the peroneus longus, 

 and, as usual, supports the two outer toes. The base of the 

 metatarsal of the hallux is broad, and its under border is pro- 

 duced into contact with that of the second metatarsal. The 

 third metatarsal is a little longer than the second ; the fourth 

 has nearly the same length, and so has the fifth, 69, by reason of 

 the backward production of the outer angle of its base. The 

 proximal phalanx of the fourth toe is the longest. Fig. 343 shows 

 how little the phalanges of ii-v differ in length or breadth. 



With the exception of the attenuated state of the third digit 

 of the fore-foot, the characters of the limb-bones of Chiromys 

 are closely repeated in other Lemuvid(B. The Pottos {Perodic- 

 ticus), however, offer an anomaly, in the fore-hand, by the 

 stunted phalanges of the index digit ; and the poUex is large and 



