320 



FIRST LESSONS IN ZOOLOGY 



antl cold, while many live on or near the surface. Again, 

 some of the surface fc^rms keep always near the shore, 

 while others never or rarely come in sight of land. Jkit 

 most of the familiar animals about us cannot live in water 



r'ir., 250. — Thf r.triKi^siaii Ijulterfly [Furnassius smint/nus) which live^ in 

 the Riicky Mountains aud Sit-rra Nuvaila, at an ahitiidc i if 5000 feet 

 and ab(,>ve. (Natural bize; from speeimen.) 



at all. They either burrow in the ground like moles and 

 gophers, or live in trees like stjuirrcls, or fly in the air 

 like birds and butterflies. 



Barriers. — f)f land animals some can live only in 

 tropical and sub-tropical regions, as the monkeys and 

 most of the parrots, some live onh' in the snowy regions 

 near the poles, as the polar bear and great walrus, while 

 many prefer neither of these extremes but live in the 

 temperate zones. Although the word " prefer " has been 

 used, it is usually true that animals which live in arctic 

 regions arc not able to live elsewhere; thev seem to be 

 adapted solely for an arctic climate, .so that the line around 

 the earth south of which there is frost and freezing weather 

 during a part of the year only is a sort of barrier beyond 

 which they cannot safely venture. And, turning to the 



