ADAPTATIONS 



thrust into a pouch or fold of skin along the abdomen, 

 where they are kept until they are able to take care of 

 themselves (Fig. 74). This is an interesting and ingenious 

 adaptation, but less specialized and 

 less perfect an adaptation than the 

 conditions found in ordinary mam- 

 mals. 



Among the insects, the special 

 provisions for the protection and 

 care of the eggs and the young are 

 wide-spread and various. Some of 

 those adaptations which take the 

 special form of nests or " homes " 

 will be described in a later chapter 

 (see Chapter XV). The eggs of 

 the common cockroach are laid in 

 small packets inclosed in a firm wall 



(Fig. 76). The eggs of the great water-bugs are carried on 

 the back of the male (Fig. 77) ; and the spiders lay their 

 eggs in a silken sac or cocoon, and some of the ground or 



FIG. 77. Giant water-bug (Ser- 

 phus). Male carrying eggs 

 on its back. 



Fio. 78. Cocoon inclosing the pupa of the great Cecropia moth. Spun of silk by the 

 larva before pupation. 



running spiders (Lycosidw) drag this egg-sac, attached to 

 the tip of the abdomen, about with them. The young 

 spiders when hatched live for some days inside this sac, 

 feeding on each other ! Many insects have long, sharp, 



