The material of the net should be some kind of strong gauze, or a loosely-woven canvas. Leno answers very well, but is somewhat easily torn, and will have to be frequently renewed. This, however, may be avoided to a great extent if, instead of sewing the gauze directly round the wire, a strip of strong calico be first attached to the frame, and the gauze then sewn to the calico; for it will be understood that any fragile material placed round the wire will soon be worn through by friction against the rugged surfaces of the rocks and stones. The net itself should not be very deep, and should have no corners; and as to the length of the handle, that will be determined by the fancy of the collector, or by the character of the ponds to be searched, but a tough walking-stick with a crook handle will generally answer all purposes, the crook being itself frequently useful for removing the larger weeds and other obstructions. [Illustration: FIG. 17.--RHOMBOIDAL NET] [Illustration: FIG. 18.--SEMICIRCULAR NET] [Illustration: FIG. 19.--THE DREDGE] Although the net, as above described, will answer the requirements of nearly all young collectors, yet there may be some, who, not satisfied with the exploration of the rocks and pools exposed when the tide is out, desire to know something of the creatures that live entirely beyond low-water mark, where the water is generally too deep for work with a hand net. To such we recommend a small dredge that may be lowered from a boat and then drawn along the bottom. A good form of dredge is shown in fig. 19, and a little skill and ingenuity will enable anyone to construct one with the help of our illustration; but, seeing that the best work is to be done on rough bottoms, it is absolutely necessary that both frame and net should be made of the stoutest materials that can be conveniently employed. [Illustration: FIG. 20.--THE CRAB-POT]