44 FIRST LESSONS IN ZOOLOGY 



into a groove or sac between the folds of skin on the 

 lower part of the tail. Here they are kept until the little 

 fishes are large enough to swim about for themselves. 

 The brave little stickleback builds a tiny nest about an 

 inch and a half or two inches in diameter, with a small 

 opening at the top. In this nest the eggs are laid, and 

 the young fish remain in it some time after hatching. 

 The male parent jealously guards it and fights bravely 

 ^\'ith would-be intruders. 



The frogs and salamanders (batrachians) and the lizards 

 and snakes (reptiles) rarely show any care for their 

 young, the eggs of most batrachians being laid in the 

 w ater and left by the female. The males of the Surinam 

 toad receive the eggs in pits of the spongy skin of the 

 back, where they remain until the young hatch. Snakes' 

 eggs are laid under logs or buried in sand, and no fur- 

 ther attention is given them by the parent. 



Among the birds, as we know, nest-building and care 

 of the joung are the rule. But not all birds make nests. 

 On the rocky islets of the northern oceans, where thou- 

 sands of puffins and auks and other maritime birds gather 

 to breed, the eggs are laid on the bare rock (fig. 27). 

 At the other e.xtreme is the tailor-bird of India, which 

 sews together leaves \\\t\\ fibrous strips, plucked from a 

 gro\\ ing plant, to form a long, bag-like nest. The nests 

 of the orioles and bush-tits are also good examples of 

 elaborate nest-making. In the degree of care given the 

 nestlings there is also much difference. The robin brings 

 food to the helpless )-oung for many da)'s, and finally 

 teaches it to fiy and to hunt for food for itself. Young 

 chickens are not so helpless as the nesting robins, but 

 are able to run about, and, under the guiding care of the 

 hen mother, to piclc up food for themselves. 



Among the mammals tlie )'ouiig are always given some 

 degree of care. Excepting in the case of the egg-laying 



