December 8, 189-'] 



NATURE 



141 



placed in its own proper jar of 90 per cent, alcohol diluted in 

 the proportion of 30 per cent, with pure water. Specimens to be 

 prepared for the cabinet require the removal of the soft parts if 

 they are still present, the cleaning off of parasitic or incrustin^j 

 growths, and, in the case of bivalves, securing the valves in a 

 convenient position for the cabinet. The different classes of 

 shells may be treated under several heads. 



Land and Fresh- Water Shells. 

 Land and fresh-water shells are much more easy to deal with 

 than marine shells. In the case of spiral shells, such as Limncea, 

 Planorbis, Paludina, Sec, the shell may first be washed clean 

 of mud or comfervoid growth, which may be conveniently done 

 with the assistance of an old tooth or nail brush. In the case of 

 these forms the easiest way to remove the soft parts is to place 

 the shell for twenty four hours in weak alcohol, after which those 

 parts can readily be removed ; but in any case where the expense 

 of alcohol is an object to be avoided, it will be sufficient to 

 place them in a small tin kettle, or other receptacle suitable for 

 the purpose, and cover them with cold water, which should then 

 be slowly brought to the boiling point. As soon as it has reached 

 the boiling pomt it may be remjved from the fire. The shells 

 should not be put into water already boiling, as it frequently 

 cracks delicate shells, and the sudden change of temperature 

 injures their polish and general appearance. 



For removing the soft parts from spiral shells the collector 

 will usually find a crooked pin sufficient. For this purpose one 

 of those long steel pins used by ladies as hat pins is convenient. 

 By heating the pointed end in the flame of a candle or alcohol 

 lamp the temper can be taken out of the steel, so that it can be 

 readily bent into any shape desired. The proper form for 

 reaching the retracted parts in a spiral shell will of course be a 

 spiral. With a small pair of plyers, different forms can hi ex- 

 perimented with, and those which are most satisfactory decided 

 upon. After the right form has been obtained, by heating the 

 pin again and plunging it suddenly into cold water, the temper 

 of the steel will be measurably restored and the instrument 

 ready for use. Similar pins in their ordinary condition are con- 

 venient for cleaning out sand or parasites from the recesses of 

 sculptured shells, and for other purposes. The attachment of a 

 gastropod to its shell is at the central axis or pillar of the shell, 

 usually from half a turn to a turn and a quarter behind the aper- 

 ture. By applying the pressure of the extractor carefully in this 

 vicinity the attachment will give way and the extractor may be 

 withdrawn, bringing with it the soft portions of the animal. In 

 large and heavy shells, in which the muscular attachments are 

 strong and deep-seated, and it is desired to obtain a good hold 

 of the animal in order to extract it from the shell ordinary steel 

 fish-hooks may be used. These may be softened by heat, 

 straightened out, and twisted into a spiral of the proper form, 

 and retempered. Then they can be securely fastened to 

 small wooden handles by the shank of the hook. In this way 

 the barb of the hook will assist in retaining the soft parts on the 

 extractor when it is withdrawn from the shell. Several German 

 firms advertise sets of implements for cleaning, cooking, and 

 extracting the animals from shells ofmollusks, but it would seem 

 to the writer that any person of ordinary intelligence and some 

 little mechanical ingenuity, such as all naturalists are expected 

 to possess, should be able to provide himself with the necessary 

 apparatus without purchasing expensive paraphernalia of this 

 kind. Shells which have no operculum require merely to be 

 cleaned alter the animal has been removed, and in the case of 

 land and fresh-water shells this is usually a very simple matter. 

 Shells which possess an operculum should retain it in the 

 cabinet, as it is often of great value in determining the relations 

 of the species, since the operculum is a characteristic feature in 

 the economy of the animal. It should be detached from the 

 body of the animal after the latter has been extracted from the 

 shell, carefully washed and cleaned, and if flat and horny may 

 be dried between two pieces ol blotting paper, under a weight. 

 This will prevent it from becoming contorted in the process of 

 drying. For removing the thick incrustation of lime and per- 

 oxide of iron which frequently forms upon fresh-water shells, a 

 few tools resembling engraver's tools or the little chisels in use 

 by dentists for excavating teeth are very convenient. A suitable 

 toot, however, can easily be made by softening and grinding 

 down an old file to a triangular point. A little experience will 

 enable the collector to become expert in scaling off the objection- 

 able matter without injury to the surface of the shell. 



Naked slugs should be preserved in alcohol, after being 



NO. 1206, VOL. 47] 



sketched in the living state. Some of the older naturalists had 

 a way of skinning slugs, inflating and drying the empty skins for 

 preservation in their collections, much as entomologists some- 

 times treat caterpillars ; but this ingenious device has nothing 

 to recommend it to a scientific collector, even if he has the 

 dexterity to practise it. The internal shell of such slugs as- 

 Limax may be represented in the collection if desired, but, in 

 any case, specimens should be carefully preserved in spirits. 



The bivalve shells, such as Unio, if taken alive, may be left 

 in the sun for a short time, when they will usually open, and, 

 the muscle connecting the two valves being cut, the valves may 

 be cleaned. It is desirable for cabinet purposes to preserve the 

 two valves in their natural position, attached to each other by 

 the ligament which holds them together in life. This ligament 

 dries to a very brittle, horny substance. Consequently the shells 

 must be placed in position when fresh in order to make a success 

 of the operation. After cleaning away the animal matter and 

 thoroughly washing the interior of the shell, it is a good plan to 

 note the locality with a soft lead-pencil upon the shell itself. 

 Then bring the two valves together in their natural position and 

 tie them in that position with a piece of tape or soft twine, which 

 should be allowed to remain until the ligament is thoroughly 

 dry. Specimens prepared in this way are more valuable for 

 exchange and more attractive to the eye than those with which 

 less care has been taken. It is always desirable, however, to 

 have some specimens with separated valves of every bivalve 

 species in the cabinet, in order that the characteristics of the 

 interior may be easily examined. 



Fresh-water bivalves are usually covered with a thin and highly 

 polished, often very elegant, greenish or brownish epidermis. 

 Sometimes the shell is so thin that, in drying, the contracting 

 epidermis splits and cracks the shelly portion so that it becomes 

 worthless for the cabinet. This often happens with marine 

 mussels, but it is almost characteristic of the thin fresh-water 

 UnionidcE. Various methods have been adopted to prevent this 

 unfortunate result. Some collectors have varnished their shells 

 immediately after they were obtained. Others have used sweet 

 oil or other oils in the hope of keeping the epidermis in a soft 

 condition. These applications are all objectionable for one 

 reason or another, as the first endeavour of the collector who 

 desires to make a really scientific collection should be to keep 

 his specimens as nearly as possible in a perfectly natural con- 

 dition. The most satisfactory substance for application to the 

 shells in question is probably ordinary vaseline, which should be 

 applied in very small quantities, so that the specimen will have 

 no greasy feeling and will absorb the vaseline sufficiently not to 

 become sticky to the touch. Glycerine, which has been recom- 

 mended by several collectors, like oil, leaves the surface sticky 

 and offensive to the touch, besides rendering it liable to catch 

 everything in the way of dust with which it may come in 

 contact. 



Very small gastropod shells need not have the soft parts re- 

 moved. If they are put into a vial of alcohol for twenty-four 

 hours, then taken out and allowed to dry, the soft parts will 

 become desiccated without any offensive odour, and they may 

 be placed in the cabinet without further preparation. It may be 

 noted, however, that if the cabinet contains many such shells, 

 care should be taken to guard against the access of mice and vermin, 

 which are apt to attack them in the absence of something more 

 attractive in the way of food. For those shells which possess 

 an operculum, after the operculum has been dried and the shell 

 cleaned and ready for the cabinet, it is customary to insert a 

 little wad of raw cotton, rolled so as to fit the aperture snugly, 

 the outer surface of it being touched with a drop of mucilage. 

 The operculum can then be laid upon this in its natural position 

 and the mucilage and cotton will retain it so without making it 

 difficult to remove for an examination of the shell if desired at any 

 time. For the preservation of eggs ofmollusks when they have a 

 horny or calcareous shell, small glass tubes securely corked are the 

 best receptacles. Most of these eggs are so small that they may be 

 preserved in a dry state or in alcohol without trouble, but the 

 eggs of some of the tropical land snails are so large that it will 

 be necessary to drill a small hole and extract the fluid contents 

 as if they were bird's eggs in order to preserve them. Such 

 eggs are the best preserved in alcohol. 



Marine Shells. 

 The preparation of marine shells for the cabinet does not 

 essentially differ from that required for land or fresh-water 

 shells, except that in the marine shells the muscular system is 



