FBESH-WATBE, CBTJSTACEANS. 287 



animals, will fall upon the surface prepared for them, and 

 commence at once, as they lie helplessly on their sides, those 

 curious twisting movements which have given them the name 

 of Fresh- water Screws. These animals are very similar in 

 appearance to the common sandhopper, to which, indeed, they 

 are closely related. They are frequently found in pairs, the 

 female being known by her smaller size, and they resemble 

 fish in their habit of keeping their heads facing the stream. 

 Fresh-water Shrimps are most useful, for not only are they 

 excellent scavengers, but they also in their own bodies supply 

 trout and other fish with the very best of foods. They may 

 be kept in either large or small tanks, where they wiU do 

 good by consuming any animal matter, which, if allowed to 

 remain in the water, woiild certainly become a source of 

 mischief. For example, should a snail die, they will quickly 

 devour its body and make a home of its shell. Of course, in 

 a large aquarium which is stocked in the usual manner, these 

 Shrimps are almost sure some time or other to be eaten by 

 the fish or other animals. The Gammari are very interesting 

 in a small tank which is given up entirely to their use. They 

 are by no means ungraceful as they dart swiftly about the 

 water, hunt its bottom in a very dog-like fashion, or cling 

 quite motionless to the weeds, with the exception of the rapid 

 movements of their respiratory organs. Their shells, which 

 from time to time they shed, are often so life-like as to be not 

 infrequently mistaken by the novice for the animal itself. 

 These crustaceans may be fed upon raw meat, a piece of dead 

 garden-worm, or almost anything of an animal nature. They 

 also feed occasionally upon aquatic weeds. They will breed 

 very readily in an aquarium which is kept expressly for them, 

 which should be stocked with plenty of aquatic plants and 

 water-snails, and at the bottom of it there should be several 

 large stones under which the Shrimps can hide. The females 

 carry their eggs attached to the under-parts of their bodies, 

 and there the young also remain for some time after they 

 are hatched. The young of these crustaceans are pretty and 

 active little creatures, and form excellent food for many kinds 

 of fish. They are of a very much lighter shade than their 



