Page:The Book of the Aquarium and Water Cabinet.djvu/152

140 some cases of an agreeable nature, and in others—as the common bed bug—of a most disgusting nature. The order readily separates itself into two great divisions—namely, the Geocorisa, or Land Bugs, and the Hydrocorisa or Water Bugs. Both divisions supply a few specimens for the Water Cabinet, but the most important are those belonging to the second class.

Among the first class in this order the most interesting is Hydrometra stagnorum, or the Water-measurer, which may be seen treading the surface of still brooks and rank pools in summer-time, in company with swarms of tipulidan gnats (Chironomi), whirlwigs, and two other aquatic bugs, the Gerris locustris and the Velia currens of Latrielle. The Hydrometra is a lively creature, a body so slender as to be little more than a black line half an inch in length, from which the long and angularly-jointed legs proceed in regular pairs. Under the microscope the divisions of the body are very plainly and prettily marked, and the terminal processes of the legs are made after the model of those water-shoes with which a certain clever Norwegian lately undertook to walk on water with nearly as much ease as on land. Whether the mechanician ever succeeded in this enterprise is not on record, but it is on record in the Book of Nature that this, and many other similarly-formed creatures, have found on the aqueous element a safe flooring for their feet ever since the first hour of creation, ere He who equipped them, had sent his Son to walk upon the waves.

Notanecta and Nepa are of the same order, but are true water-bugs, formed for diving and sub-aqueous life.