OBSERVATIONS ON SOME NEW BRUNSWICK FISHES. 39 



proving that it, too, possesses the remarkable vitality and 

 powers of adaptation to altered conditions of life, so charac- 

 teristic of the whole family. It is the largest of the stickle- 

 backs, being fully four inches long, and has but two, rarely 

 three, dorsal spines. These are hinged at the base and 

 capable of being so set as to resist great pressure before 

 yielding. The tail is keeled laterally with a sharp ridge, the 

 function of which is not understood. 



Wherever found in large numbers, these little creatures 

 play an important part in the destruction of other species- 

 Active, bold and greedy, they never tire hunting up spawn 

 and fry in the shallow waters they frequent, and into which 

 the helpless young of other species flee for safety from larger 

 enemies.* Indeed, so marked is this spirit of destruction 

 that they will attack and kill their own young — a singular 

 fact, as under certain conditions, no other fish evinces more 

 parental affection. Many not only build nests for the recep- 

 tion and safety of their spawn, but the males stand guard at 

 portals, fanning the water with their fins and tails to keep 

 up a healthy circulation, which cannot otherwise be had, as 

 the nests are made in sluggish or altogether stagnant water. 

 They are even said to enter the nests from time to time and 

 stir up the eggs thus securing their more uniform aeration. 

 These extraordinary precautions, in such strong contrast with 

 the usual indifference of fish to the fate of their offspring, are 

 seemingly suggested by a sense of their own destructive 

 habits. 



Their undue multiplication is chiefly prevented by certain 

 birds, such as the blue heron (Ardea herodias, Linn.); 

 American bittern {Botaurus le?iiiginosus, Motag.) ; green 

 heron {Ardea virescens, Linn.); yellow legs {Totanus flavipes, 

 Gmel.); and other waders, besides the belter kingfisher {Ceryle 

 dlcyon, Linn.), which incessantly prey upon them in every 



* A small stickle-back, kept in an aquarium in England, devoured in five hours 

 seventy-four young dace, which were about a quarter of an inch long and about as- 

 thick as a horse hair. Two days after it swallowed sixty -two, and would likely- 

 have eaten as many every day could they have been procured. 



