Feet of Birds. 5 7 



The tail bones are short and compressed, forming 

 a ploughshare-like process ; the pelvic bones are long, 

 and stretch along the spine fore and aft to an extent 

 proportionally unmatched in the rest of the sub-king- 

 dom (fig. 23). The two pubic bones do not unite in 

 the middle line in front of the pelvis except in the 

 ostrich, but always remain separate and open. The 

 thigh bones are short. The leg-bone consists of two 

 parts, which in adult birds are indistinguishably united. 

 Of these the largest part is the tibia, or leg-bone 

 proper, the lower end consists of the astragalus, or 

 first bone of the tarsus or ankle. The lower part of 

 the shank of a bird consists of the remaining tarsal 

 and metatarsal bones elongated into a single shaft, 

 and below this are the toes, of whiqh usually four are 

 developed. The innermost of these or the hind .toe 

 consists in general of two joints or phalanges, the 

 second (inner) toe is made up of three, the middle 

 or longest toe, of four, and the outermost toe of five 

 phalanges. The shapes and dispositions of the toes 

 vary with the habits of the birds ; thus, birds of prey 

 have stout, grasping feet, with sharply hooked claws. 

 Climbers, like woodpeckers and parrots, have the 

 outer and inner toes turned backwards and the other 

 two forwards. In swimmers, all the forward toes are 

 webbed, while in the scraping birds the toes are 

 short, stout, and armed with blunt nails. Many of 

 the bones in the body of a bird are hollow, and in- 

 stead of containing marrow they are lined by a deli- 

 cate membrane and contain air, which is conducted 

 into them from the respiratory organs by thin walled 

 canals. This condition is specially exhibited in the 



