300 THE ANATOMY OF VERTEBRATED ANIMALS. 



The ossa innominata are elongated, and their long axes, 

 on the length of which depends the proportional size of the 

 " quarter " of a Horse, form an acute angle with the spine. 

 The crests of the ilia are wide and directed transversely, and 

 the symphysis pubis is very long. 



Fto. 99. — The OBsa innominata of a Tlorse viewed from the left side and behind.— 1. The 

 crest of the ilium. 2. The surface by which it articulates with the sacrum. 4. The 

 acetabulum. 6. The ischium. 



The femur has a lar^'c third trochanter (°, Fig. 100), into 

 which the glutceus tiiaxunus is inserted. Its head presents a 

 deep pit for the round ligament, and there is a peculiar and 

 very characteristic fossa ('") on the inner and posterior face of 

 the distal moiety of the bone. 



The proximal end of the fibula is reduced to a mere rudi- 

 ment ; its shaft is not represented by bone ; and its distal end 

 is anchylosed with the tibia, and has the appearance of being 

 an external malleolar process of that bone. The distal end 

 of the tibia presents two deep, obliquely-directed concavities, 

 which correspond with the convexities of the astragalus. 



There are six or seven tarsal bones, according as the ento- 

 and meso-cuneiform bones remain distinct or become anchy- 

 losed. The astragalus (Fig. 93 A, 94 B) is extremely charac- 

 teristic. It presents two convex ridges separated by a deep 

 fossa, and directed obliquely from behind and within, forward 

 and outward, to the tibia ; and it has a nearly flat distal face, 



