AND PHYSIOLOGY* 



93 



consisting only of a single bone. The Elephant has five toes, 

 the Hog four, the Rhinoceros three, the Cow two, and the 

 Horse one. Sometimes the longest finger (paddle) of the 

 Whale contains eleven bones. In burrowing and swimming 

 animals the fore-feet are generally the largest, and among some 

 quadrupeds the reverse is the case. The posterior extremities 

 of quadrupeds are usually less modified than the anterior ones, 

 as they are used mainly for support and progression. 



OSTEOLOGY OF BIRDS. 



201. VertebrsB, Cervical, Dorsal, Caudal —Birds exhibit 

 several peculiarities in their Spinal Column. The number 

 of Cervical Vertebrae is much greater than in mammals, 

 giving them long and flexible necks. (Fig. 106, p. 94.) 

 The number is between ten and fifteen, but the white Sw 7 an 

 has twenty-three. The Dorsal Vertebrae vary in number 

 from seven to nine, and admit of but little motion upon 

 each other, many of them being frequently anchylosed to- 

 gether, as in the human sacrum. (Fig. 107, p. 95.) The 

 design of this is to give the firmest point of attachment to 

 wings that can be secured. The Caudal Vertebras are hol- 

 low and form a complete canal for the spinal marrow. The 

 last one has a large disc-shaped process upon it for the sup- 

 port of the long feathers of the tail. 



202. Bones of Head, Os Quadratum, Jugal Bone.— 

 The bones of the head correspond in number and position 

 for the most part with those of the mammalia. (Fig. 108, 

 p. 95. ) They are, however, united together at a very early 

 period, and the sutures can not be recognized except in very 

 young subjects. One point of difference between these skulls 



What are some modifications of Phalanges? 201. Compare the Cervical Vertebra? o! 

 Mammals with those of Birds. What number of Cervical Vertebrae has the Swan? Why 

 are the Dorsal Vertebra? usually firmly fixed together ? What peculiarity of the Cauda! 

 Vertebra ? 202. What can be said of the Sutures in the head of birds ? 



