PARENTAL CARE AMONG FRESH-WATER FTRHES. 4V> 7 



steady themselves l)v theii- tails, and then suddenly dart sti'aii»ht at 

 the lips of their intended prey, from which they bit pieces out. 

 These attacks were continued until all the roach had V)een killed, 

 when they were eaten by their conquerors.'' 



Another instance of insatiable voracity has been recorded by Baker. 

 One devoured in five hours 74 young dace, which were a quarter of 

 an inch long and of the thickness of horsehair. Two days afterwards 

 it swallowed 02, and would probably have eaten as many every day 

 could they have been procured for it. 



Such are the main facts respecting the general habits of the stickle- 

 backs, but their chief interest to us are the extraordinary nests which 

 they make and the still more extraordinary provision with which 

 nature has endowed the males to make those nests. 



AVhen sj^ring and warm w(;ather are well advanced males and 

 females become impressed with the instinct to reproduce their kind, 

 jind the whole organization is modified accordingly. The female's 

 abdomen becomes distended with eggs, and the male, who had been 

 silvery Avhite during winter, assumes a brilliant livery, develops from 

 the urinary bladder and kidneys the material for a peculiar thread- 

 like substance, and prepares to make a nest for the recejition of eggs 

 of such females as he may be able to influence. 



The peculiar secretion from the kidneys deserves some notice here, 

 for it is unique and only known in the sticklebacks. Tt was first 

 fully described by Karl Mobius (1885) and soon afterwards by John 

 Ryder (1882) and E. PI Prince (188.5). The last has not only given 

 an excellent account of the peculiar structure, l)ut some apt illustra- 

 tions, and these are reprotluced herewith. (Plate T.) 



