10 COMMON BRITISH ANIMALS 



are flesh- eating mammals living in the sea. Sheep 

 and deer are grass-feeding or herbivorous mammals. 

 The manatee and dugong are herbivorous mammals 

 living both in fresh water and the sea. Rats and 

 mice are gnawing mammals. 



There are other groups of backboned animals 

 which do not feed their young with milk ; some 

 of these have warm blood, while others have cold. 

 We shall find that the building plan of all backboned 

 animals is the same, their forms varying only in 

 detail. First, there is the box or trunk containing 

 the heart, lungs, stomach, and other organs; this 

 box is placed on four legs. Along the top of the 

 box runs the backbone, a series of thick hollow bones 

 which contain and protect the marrow or spinal cord. 

 'Jliese bones project beyond the box at the back to 

 form the tail, and also extend beyond the box in 

 front forming the neck, which carries the head, a 

 smaller box containing a special portion of the spinal 

 cord called the brain, the central nerve office whence 

 messages are serit out to the limbs and all the organs 

 of the body. Upon the head are placed such organs 

 as the eyes, nose and mouth, which carry messages 

 to the brain. This, roughly, is the plan Nature has 

 adopted in making all the backboned animals. No 

 single plan prevails in the construction of animals 

 without backbones. There is much more variation 

 in their design. 



The backboned animals have usually two rings 

 of bones round the trunk : one called the shoulder 

 girdle where the arms or fore-legs are attached, and 

 another called the hip girdle carrying the hind legs. 



