486 SOCIAL LIFE OF ANIMALS 



or three weeks. Parasitic egg-laying. A South American duck 

 {Metopiana) lays Its eggs in the nests of other birds such as the coot 

 and sea-gull, while the European cuckoo lays her eggs in the nests of 

 other birds. The American cowbird has the same habit of seeking 

 foster parents for her offspring. (See Friedmann, H. 1929. The 

 Cowbird. C. C. Thomas Pub.) 



(2) Father Families. — The male obstetric frog {Alytes obstetri- 

 cans) carries the eggs with him in a long string wound around his 

 hind legs until the larvae emerge. The male Rhinodenna carries 

 the eggs in his gular vocal sac until the metamorphosis of the young 

 is complete. In some species of frogs the tadpoles are carried on the 

 back of the male. 



The male stickle-back fish builds a nest and entices several 

 females to deposit their eggs in it. Eggs and young are guarded 

 by the father. In a number of fish species the male seizes in its 

 mouth young that have strayed away and brings them back to the 

 nest. It is said that the male Amia (the bow fin) leads its family of 

 young for four months.^ 



(3) Mother Families. — The females of some species of leeches 

 carry their offspring about, the young attaching themselves to the 

 body of the mother with their suckers and always returning to her. 

 The female earwig {Forjicula) guards her eggs and young in a hole 

 which she digs herself, collecting them together if they get scattered. 

 The female mole cricket digs a hole for the eggs and guards them, 

 but turns cannibal occasionally. 



In crayfish and spiders the mother carries eggs and young around 

 with her. Female scorpions carry young on their backs. In a 

 number of species of fish the females lead their young for some time 

 after hatching. In some species of Chichlidae the female carries 

 the eggs in a pocket on the back and the female Pipa (a toad) carries 

 its young in pouches of skin on its back until metamorphosis has 

 occurred. ^a^ ^^AitM^M^^ ^p(lU4^^ 



Female crocodilia watch over the eggs^open them by means of a 

 well-developed egg tooth, ^|^lead the young to the water. Mother 

 families are the rule among birds. Mother families are found in the 

 cat family, in foxes, polar bears, and seals. 



(4) Child Families. — Certain processionary caterpillars {Thau- 

 matopaea) , emerging from the same mass of eggs, remain together 



2 Consult Gill, Theodore. 1905. Parental Care Among Fresh Water Fishes. 

 Smithsonian Rep., pp. 403-531. 



