the mention that a few large mussel-like shells are inhabitants of our fresh waters, and great is his haste to be up and again doing, in the hope of adding some of them to his stock. But in vain were his many attempts to find them in the pond which had already yielded us such a variety. "Do they live here?" is at last the anxious question. "No; but let us away to yon sluggish brook, for it is in such that we may expect to meet with them." "Now I see them. Are not those their ends just peeping above the mud?" And full of eagerness he dashes in the dredge, but with little result, excepting that of a dead shell or two. "Oh! how can I get them? Shall I take off my shoes and socks and wade for them?" "Well, you might secure them that way, and sometimes it is the only way, but on this occasion I do not think it necessary. Come, we will move a little higher up, where the stream is clear, and the shellfish undisturbed. Observe the gaping ends of the shell, and thus I push the end of the stout rod between the partially-open valves; now they close upon the stick, and so we bring our prize holding on to the stick to the bank." "You will recollect," addressing my companion, "that in the muddy pond we have just left, we chiefly got small bivalves and only a few snail shells. I have already told you that water shells differ much in their habits, and that consequently our search for any particular species, or set of species, can only be successfully carried on when that knowledge is our guide. Those little bivalves, and a few of the snails that we have gathered, habitually live at the bottom, and will of course be brought up in the dredge when that implement is dragged over it; but there are many shells which live at or near the surface, and which feed on the submerged and floating plants. Therefore we must seek out a weedy pool if we would increase the variety of our collection." Such a spot is reached; and the dredge is brought into requisition, anon to snatch up a floating snail, or again to sweep over and through the plants, varying our occupation by dragging to the margin the tangled masses of weeds; by all of which means a considerable number of the class of air-breathing water snails was obtained--admonishing my young friend that this last plan does very well when the plants grow in dense masses, because when thus interlaced they form a natural net to catch those snails which on the slightest disturbance lose their hold upon the weeds, and which would otherwise fall to the bottom. Yet another plan remains to be pursued, one by which the few small shells hiding among the roots of the plants may be secured. Obviously the dredge misses such; but by pulling up the plants by their roots, and well shaking them in the half-sunken sifter, we yet after all obtain them.