Crayfish and shrimp should by all means have a place in the aquarium. They are to be found in most streams by turning over the stones, and they are easily caught. Of the fresh-water crayfish we have one species in this country which seems to be spread over a pretty wide range, and is well known to anglers as a killing bait for bass and some other fish. Its scientific name is Astacus Bartonii. It breeds freely, and the young are curious little creatures. The old females may frequently be found with a number of their young adhering to their bodies under the tail; and when such a specimen can be captured it is well worth while to give her a separate tank, and try to rear the young.
In addition to the crayfish, the grammarus is well worthy of a place; and so is the brachripus. The grammarus, or freshwater shrimp, is a favorite food of the trout, which always grows to a larger size, and has a superior flavor where they abound.
Insects, crustaceans, and reptiles are all apt to make efforts to escape during the night; and therefore the aquarium containing them should be carefully covered every evening, so as to prevent this. The best cover is a light wooden frame, over which fine wire gauze is stretched.