FISHES 427 



region, and are carried about till the time of hatching. Another 

 instance is afforded by a curious little Pipe- Fish {Solenostoma) 

 which inhabits the Indian Ocean, and, like other related forms, is 

 distinguished by its tubular snout. The large pelvic fins of the 

 female overlap each other, and also fuse with the adjacent skin so 

 as to constitute a backwardly opening brood-pouch, within which 

 the eggs develop. A large number of threads grow out from the 

 inner side of this pouch, and among these the eggs are entangled. 

 Fishes often make very exemplary fathers, and among the 

 most interesting instances of parental instinct are certain species 

 allied to the two last mentioned. In some of the Cat-Fishes, 

 for example, the male guards the hollows in 

 which the eggs are laid, while in other mem- /^^^ft^ 



bers of the same family (e.g. Arius) he carries v^0^^^^ 



them about in his gill -chambers till the time <^>^ ^Km^ 



of hatching, a situation which ensures not only __^^^^ 



protection but a constant supply of fresh oxy- ""K, ^K.l' 



genated water. In the Greater Pipe - Fish ^^^ 



{Syngnathus acus) and the little Sea - Horse ^^ ^K\ 



[Hippocampus, fig. 954) the male possesses a ^^^^^ 



brood-pouch on the under side of his body, Rg. 9S4.-Maie sea-Horse 

 rather far back. Within this the eg-gs hatch (^'^i*""""/"-;)- a °p'="'"s 



00 of brood-pouch. 



out. In the former case it is said that the 



young fishes make use of the pouch as a refuge for some time 



after they begin their free existence. 



The male fish sometimes constructs regular nests for the 

 reception of the eggs. This is the case, for example, in the 

 beautiful little Paradise Fish {Polyacanthtis or Macropomus viridi- 

 aurahis), distinguished by its bright colours and large forked 

 tail. It has long been domesticated in China, from which country 

 it was introduced into Europe, and probably differs a great deal 

 from the wild parent species, of which nothing is yet known. 

 At the time of spawning, the male constructs a floating nest of 

 froth, bringing down air-bubbles and entangling these in slime 

 to make a bowl-shaped construction. To this he conveys the 

 eggs, and watches jealously over them till the time of hatching, 

 and even afterwards, for it is said that if one of the tender fry 

 escapes from the nursery he carefully takes it back again. 



Male Sticklebacks (GasterosteidcE) construct muff-shaped nests 

 from bits of weed, glued together by sticky threads which their 



