BONY FISHES 



291 



opening of the nest. 



Here it watches the eggs with great care, and by- 

 rapid fanning movements of its pectoral 

 fins provides them with a constant supply 

 of fresh water. It also takes care of the 

 young for some time after they are 

 hatched. If one of them should venture 

 too far, the cautious parent catches it in 

 its mouth and throws it back into the 

 nest. This habit of looking after the 

 young brood explains the small number 

 of the eggs in this species, and also the 

 situation of the nest in strata of the 

 water which are poor in oxygen. 



In the spots frequented by the 

 three-spined stickleback we also usually 

 find the Nine-Spined species (G. pun- 

 gitius). This species always builds its 

 nest among water-plants. During the 



Thkee-Spined and Nine-Spined Stickleback. (Slightly less than natural size.) 

 M., Male, W\, female, of the three-spined species ; gSt., nine-spined stickleback. 



spawning season the abdomen of the male is always of a velvety-black 

 colour. 



