4410 Fishes 



hair-like Conferva; a few floating plants spread over the surface of 

 the water, and innumerable Entomostraca, and other small Crustaceans, 

 as well as various animalcules, swarm in all parts ; the minute, but 

 deadly, poison-armed Hydra also prevails where food is so plentiful ; 

 and a solitary individual of the great water-beetle {Dytiscus margina- 

 lia) rambles over its watery domain, lord and master of all. Several 

 of the fresh-water Mollusca also people the trough, which on the 

 whole has much the appearance of a miniature pond. Into this new 

 home were put four or five sticklebacks last May, and they at once 

 made themselves perfectly at ease. One, without the least hesitation, 

 took possession of a certain spot, which it guarded with the greatest 

 pertinacity, attacking vigorously any of its companions that might 

 happen to approach the chosen locality. The beetle too, which some- 

 times came slowly paddling by, was pounced upon and unceremo- 

 niously tumbled over; but secure within his scaly armour, as the 

 knights of old, he little heeded the onslaught of his naked assailant; 

 so, overpowering all opposition, he scrambled onward in his undevi- 

 ating path. 



This fish was rather small, had the throat of a bright red colour, 

 and the eyes of a brilliant bluish green. At first, all the others were 

 pale; but in the course of a few days, one of them gradually assumed 

 the rich hues of that just described, and soon afterwards it also be- 

 came attached to a spot, taking up its abode in one of the corners of 

 the trough. On examining attentively the two selected localities, a 

 nest was found in each, composed of a collection of delicate vegetable 

 fibres, resting on the bottom of the trough, and matted into an irre- 

 gularly circular mass, somewhat depressed, and upwards of an inch in 

 diameter; the top being covered over with the same materials, and 

 having in the centre a large hole. The fishes scarcely ever strayed 

 from their nests, but were constantly on guard, defending or repairing 

 them ; they were perpetually prying into the hole at the top, and 

 thrusting their heads right into it. On one occasion, one of them en- 

 tered by this hole, and slowly forced itself right through the side of 

 the nest; as it gradually moved onwards, its body had a peculiar 

 lateral vibratile motion. They would frequently seize hold of the 

 nest and give it a violent tug, shaking and tearing loose the vegetable 

 matter of which it was composed ; at other times they would carry to 

 it, in their mouths, fine Conferva-stems, and press them with consi- 

 derable force into the walls of the nest, or thrust them into the hole, 

 which by this means was sometimes partially concealed. Occasion- 

 ally, each was observed hovering over its nest, with the head close to 



