26 Mammalia. 



insertion of the ligamentum teres ; it is generally imperforate 

 (cf. XV.). From the anterior or upper border of the pubic 

 bones there frequently arises a pointed spine-shaped eminence 

 (eminentia ilio-pectinea), which is the first indication of the 

 Marsupial bone (cf. iv. xiv. xv.). The Femur retains more of 

 the human form in the different orders (cf iv. vi.) than does 

 the humerus : the external trochanter is often very large, and 

 extends beyond the head of the bone : the internal trochanter 

 is occasionally wanting: a " third '* trochanter, a strong pro- 

 cess more or less in the middle line, is found in a number of 

 animals (cf. ix.). Whilst in Bimana the axis of the femur 

 deviates little from that of the vertebral column, in all other 

 Orders (including the highest Catarrhina, vk.j the tail-less 

 Apes), the femora are bent more forwards, and form an ob- 

 tuse angle with the pelvis. A Patella is very generally met 

 with. In the leg the Tihia is always the principal bone, and 

 main support of the femur. The Fibula presents many varie- 

 ties (cf. XV.), and is often very rudimentary (cf. iii, iv. viii, 1.). 

 The average number of the Tarsal bones is seven, and they 

 are generally separate. The os calcis has commonly a long 

 process for the attachment of the tendon Achilles (cf. iv.). 

 The Metatarsals vary in number ; those of the principal toes 

 in the leaping animals are long, and partly united together 

 (cf. v.). The same remarks apply to the toes as made above 

 on the fingers. Among Quadrupeds the Elephant furnishes 

 an example of the pentadactyle foot ; the Hippopotamus of a 

 tetradactyle foot, having digit i. (inner) withdrawn; the 

 Rhinoceros of a tridactyle foot, having digits i. and v. 

 (outer) withdrawn ; the Ox of a didactyle foot, with digits 

 i. and v., and ii. (index) withdrawn ; and, lastly, the Horse, 

 of a monodactyle foot, having digits i. and v., and ii. and iv. 

 withdrawn. 



