REPRODUCTION AND SEX 



563 



his gill-covers, or washing off mud with energetic strokes of his tail. 

 Some male fishes like the Cichlids put the eggs in their mouth, so 

 that they may be quite safe. This is going a long way. Very well 

 known is the pocket of the male sea-horse, so attractive an inmate 

 of every large marine aquarium. When the eggs are liberated by the 

 female, they are received into the skin-pouch formed on the ventral 

 surface of the male ; and there they are carried until the young ones 

 hatch out. What a motherly father is the sea-horse! 



Apart, perhaps, from Darwin's little frog {Rhinoderma darwini), 



Fig. 89. 



The Head of the New Guinea Fish, Kurtus [after Weber). The upper figure (1) 

 shows the growth of the bony process (BP), forming a hook. The lower 

 figure (2) shows the bunch of eggs (E) fastened in the hook, which has 

 become a ring. 



which is original enough to cradle the eggs in his croaking sacs, the 

 case of Kurtus appeals to us most. In this New Guinea freshwater 

 fish the male develops at the breeding season a bony process on 

 the top of his skull, which grows forwards and downwards like a 

 bent little finger. The eggs are few in number, and they are entangled 

 by enveloping filaments in a floating double clump, like a double 

 bunch of grapes. The male butts against the eggs and gets them 

 under the process on his skull just before its hook becomes an eye. 

 So he carries them about on the top of his head until the young ones 

 emerge. A case like this makes one doubt whether there is not some 

 missing psychological factor in our customary treatment of organic 

 evolution. 



