144 



VERTEBRATE ZOOLOGY 



"eels" of the Catosteomi, for they are much like greatly attenuated 

 Sea-horses. 



The breeding habits of all members of the sub-order are peculiar. 



FIG. 81. Gasterosteus aculeatus. xl. (From Boulenger, after Goode.) 



In the case of the Stickle-backs the male builds a nest out of green 

 grasses and kindred materials, leaving a front and a rear entrance. 

 When the nest is complete he goes a-wooing and 

 induces a female to enter his nest and lay her 

 eggs there. As soon as she leaves by the back 

 door he enters by the front and fertilizes the 

 eggs. Usually several other females are em- 

 ployed in the same way until the nest is filled 

 with a sticky mass of eggs. He then watches 

 over the nest until the eggs are all hatched. Sea- 

 horses carry to a higher degree of specialization 

 this paternal solicitude for the welfare of off- 

 spring, for, instead of building a nest and guard- 

 ing the eggs, the male uses a part of his body, 

 a brood-pouch on the abdomen, as a nest. Ac- 

 cording to Jordan, the female lays her eggs on 

 FIG. 82. Hippo- the sea-bottom, and the male, after inseminat- 



id!UC ing them> transfers them to the brood -p uch and 



pouch (mp). a, anus; carries them about until they are hatched, thus 

 b. a, branchial aper- making of himself an animated incubator. 

 " Some of the Sea-horses are provided with an 

 elaborate camouflage in the form of leaf-like 

 processes (Fig. 83) colored like sea-weed and are practically invis- 

 able in their native haunts. The Sea-moth, another member of the 

 Catosteomi, is almost as fantastic as the Sea-horses. It is covered 



