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variety of form in birds' tails is due to the arrangement of these 

 feathers, which are merely extensions of the outer skin, rather 

 than to any difference in the inner framework. 



Birds, as a clasp, are noted for their aesthetic faculties ; they 

 have an eye for the beautiful. Hence we find various forms of 

 purely ornamental tails, often belonging to the male bird only. 

 (Such are those of some kinds of humming-birds ; also that of the 

 male of the Australian lyre-bird. In the cemmon 

 towl, the cock has a specially ornamental tail. But the strangest 

 kind of adornment is that practised by the Motmots of South 

 America. These birds aitificially beautify (as they fancy) their 

 own tails, by picking off parts of the feathers with their beaks, 

 according to a certain fashion of their c>wn invention. 



In some birds the tail is specially modified for use, not ornament. 

 Thus, in Woodpeckers it serves as a prop in climbing trees ; the 

 end of the quills being stiff and pointed, to catch against the bark» 

 The very same thing occurs in the Creepers, which belong to a 

 different order, quite separate from the Woodpeckers. 



The tails of Mammals are built on the same plan as those of the 

 lower Vertebrates ; but the bones are mostly simplified ; for the 

 spinal cord stops short, and the neural arches often extend only a 

 short distance down the tail. The skin is generally covered with 

 hair. But they differ very much from each other, according to 

 the different uses to which they are put. Thus, the Kangaroo has 

 a think muscular tail, which supports the animal in an upright 

 posture, and helps it in hopping. The African Aard-vark and the 

 scaly Pangolins have likewise thick tails, like those of Reptiles. 

 In the Otter we see a return to the original function of the tail ; 

 it is flattened, so as to form a swimming organ. In the Beaver,, 

 and also in the Whales and Porpoises, it is flattened out in the 

 opposite direction, namely, horizontally. 



A common form of tail among land mammals is the long furry 

 or bushy kind, 's\hich has various uses. In the Cat and Dog it seems 

 to serve as an outlet for emotion, and a means of expressing the 

 feelings. In some breeds of Sheep the tail has become a mere 

 reservoir of fat, like the hump of a camel. In the Squirrel it has a 

 singular use, as an overcoat or parasol. The word " squirrel " is- 

 a diminitive of the Latin sciurus, which comes from the Greek s/da,. 

 a shadow, and oura, a tail ; so the name " squirrel " means 

 " little shadow-tail." The great Ant-eater has an enormous, 

 development of hair on its tail. 



Another shape of tail is the long and thin, with a tuft at the 

 end ; seen in the Ox, Donkey, Camel, and Giraffe. This is often 

 very useful to drive off the flies. But in some jumping animals,, 

 as the Jerboas, it acts as a balancing-pole. 



