SKELETON OF LOWER LIMB. 



and in some Mammals, e.g. the Cats. It may, however, be 

 very wide, as in the Sloths and Wombat and Cape Ant- 

 eater. 



This bone in man is peculiarly shaped in relation to his 

 erect posture. 



Thus, comparing man's tibia with the same bone in other 

 members of his own order (Primates), we find that it is longer 

 as compared with the spine than in any other genus except 

 Hy I abates and Tarsius, and longer as compared with the 

 radius than in any except Hapalc and Tarsius. 



On the contrary, its length as compared with the femur 

 is less than in any other Primate. 



The tubercle of the tibia is probably at its maximum of 

 distinctness in man as compared with the rest of his class, 

 and the articular surfaces for the 

 condyles of the femur occupy a 

 maximum proportion of the upper 

 surface of the tibia. 



The sharpness of its crest in man 

 exceeds that of any other Primate, 

 and the descent of the posterior 

 border of the articular surface for the 

 astragalus below the anterior margin 

 of that surface is peculiar to him. 



The tibia may be very much 

 curved, e.g. in the Ornithorhynchus, 

 yet it may be straight and exces- 

 sively long, as in many Birds. 



The crest may project very promi- 

 nently and sharply at the upper end 

 of the bone, as e.g. in Ruminants, the 

 Kangaroo, and Hare. 



The tubercle of the tibia may be 

 enormously produced upwards into a 

 long pointed process, as in certain 

 Birds, e.g. the Grebe and Divers. 



in some forms nearly allied to man, 

 as the Orang, the articular surface of 

 the malleolus forms an obtuse angle 

 with the inferior surface of the tibia. 



The tibialis posticus groove may be much deeper than in 

 man, the portion of bone separating it from that for the flexor 

 longus pollicis pedis having thus the appearance of a promi- 

 nent process. Such is the case in Nycticebus. 



FIG. 172. LEG-BONES OF 

 THE DIVER (Colytnbns). 



I, fibula ;f, femur ; t, tibia, 

 with p, its enormously pro- 

 duced tabercle. 



