VERTEBRATA MAMMALIA, 



27 



The number of vertebrse in this division is generally 

 seven, whether the neck be long, as in the giraffe, or 

 short, as in the whales. The only exceptions to this 

 rule are, the three-toed sloth, which has nine neck bones ; 

 and the manatee, which has six. 



2. The dorsal (Lat. dorsum, the back) region. The 

 number of vertebrse in this* region varies from ten to 

 fifteen or more. The usual number is twelve or thirteen. 

 To the dorsal vertebrse the true ribs are attached. 

 These enclose the cavity of the chest, and are united . 

 in front by cartilages to the sternum or breast bone. 



FHJ. 4. DORSAL VERTEBRA WITH ATTACHED RIBS. 



act, neural arches; snx, neural canal ; v, vertebral centre; a 'a', ribs enclos- 

 ing the visceral cavity, snf; b l b', cartilages; c', sternum. 



3. The lumbar (Lat. lumbus, a loin) vertebrse occupy 

 the region of the loins. They vary in number from four 

 to seven. There are four in man. 



4. The sacral bones which follow vary from one to nine 

 in number. They are anchylosed, or immovably joined 

 together, so as to form a single bone. 



5. The caudal (Lat. cauda, the tail) or tail vertebrre 

 range from four to forty-six. They move more freely 

 upon, one another than the other vertebrse. 



