One more observation and I have done. Sometimes one comes across an insect whose rigid wings seem to defy all attempts to set; in such cases just press firmly at the back part of the thorax, between that and the abdomen, towards the pin, and the wings will sometimes fly open of their own accord, or will allow of their being easily set in the required direction, which should always be set well forward.
VII.
LAND AND FRESHWATER SHELLS, ETC.
By Professor Ralph Tate, F.G.S., etc.
A young friend, desirous of entering upon one of the most accessible natural history pursuits, that of the study of Land and Freshwater Molluscs, begged of me some practical hints on the collection and preservation of these objects of our woodlands, waysides, and watercourses. Believing that this kind of work offers a good stepping-stone to the study of nature in its more extended forms and complicated relations, I was most anxious to help my tyro naturalist, and that beyond his utmost expectations, as I made a few initiatory trips with him in a search for the coveted treasures.
Our equipment was simple and inexpensive, consisting of a block-tin saucepan finely perforated at the bottom, about six inches across, and having a hollow handle of a size to receive firmly the end of a common walking-stick—such a dredge or a sifter will cost ninepence or a shilling at a tinman's; secondly, of a pocket lens; and lastly, of a variety of boxes, and a bag to contain specimens of different sizes. Thus provided, our first excursion had for its object an examination of certain neighbouring ponds and streams. My pupil, guessing the use of the perforated saucepan, makes his way to the nearest pond, fixes the improvised handle, dashes in the sifter with impatient ardour, and having brought up a quantity of mud from the bottom, looked upon the oozy mass with despair. Patience, my lad! Remember that the pleasure of success in science is the higher the greater the labour expended in obtaining the objects of our search. Expect failure now and again, but do not be disheartened. Ohne Hast ohne Rast, should be the motto of every naturalist. Now, shake the tin in the water, keeping its rim just out of the water, dipping it down now and then. That is well; thus you see that you have cleared off the mud, and what you want is probably left behind along with the rubbish. What, nothing! Come, try again; but this time scrape the sifter along the surface of the mud, and I am confident that you will find something to reward you, and with much less trouble and display of temper. In this way, after repeated trials, a number of shells were secured and transferred to the boxes. Then, after the first gush of excitement is over, we retire to an adjoining bank to con over the spoils, and I to make mention of the various habits of freshwater snails, and consequently of the different modes of search. My young friend's enthusiasm is aroused by 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.