MOLLUSCA OF MICHIGAN— WALKER. 449 



CLEANING AND PREPARATION OF SPECIMENS. 



The larger Helices should not be put into alcohol unless desired for ana- 

 tomical purposes, as it is almost impossible to remove the animal after it 

 has become hardened. They should be boiled as soon as possible. Dead 

 snails have a fragrance peculiar to themselves, and seldom make good speci- 

 mens. The water should be boihng, not simply hot. Species of about the 

 same size should be boiled together in order that the operation may be suc- 

 cessful. A small wire strainer with a long handle is very convenient for 

 holding the snails while boiling. If dropped directly into the water, there 

 is apt to be trouble in fishing them out and they are likely to be boiled too 

 much. The time varies according to the size and the species, some requiring 

 more time than others. If not boiled enough, the muscular attachment to 

 the shell will not be loosened, and the animal will not "pull" at all. If 

 boiled too long, it is apt to break in two and give a good deal of trouble 

 before extraction. The time required varies from ten seconds for a species 

 of the size of Polygyra monodon to sixty seconds- for P. alholabris. It is well 

 to experiment a little at first with a specimen or two of each kind until the 

 proper time is found. Only a few should be boiled at a time, as they ''pull" 

 easier while warm. When boiled, the animal should be slowly and care- 

 fully pulled out. Too much haste is apt to cause the animal to break apart, 

 leaving the apical whorls still in the shell. The curved points of the col- 

 lecting forceps are convenient for extracting the animals and hooks of vari- 

 ous sizes can be made from safety pins. By tying these on to small wooden 

 handles very effective instruments can be made. Small hooks of various 

 sizes fitting into an adjustable handle are most convenient and can be ob- 

 tained from any dealer in dental instruments. A small, fine-pointed, dental 

 .syringe is indispensable for this work. If the animal cannot be started 

 with the hook, or if it breaks in two, a jet of water from the syringe will usu- 

 ally solve the difficulty. When the apical whorls are left in the shell, they 

 can sometimes be started by holding the shell carefully in hand so as not 

 to crush it, and then striking the fist sharply on the thigh of the operator. 

 In case very desirable specimens get into this predicament, putting them in 

 alcohol for twenty-four hours will contract the remnant of the animal suffi- 

 ciently to enable the successful use of the syringe. Many of the species 

 have the aperture so obstructed with teeth, that it is difficult to extract the 

 animal with the hook. In such case a vigorous use of the syringe will force 

 enough of the body out of the shell to enable the hook to be used. Fre- 

 quently the whole animal can be forced from the shell in this way, especially 

 in the smaller forms. Patience and perseverance will clean nearly every 

 specimen. When the animal is completely extracted the interior should be 

 thoroughly washed out with the syringe. A small piece of sponge on the 

 end of a fine copper wire, which can be bent in any direction, is very useful 

 for removing the mucus, which is apt to adhere to the interior of the shell. 

 This should always be carefully attended to, as it will greatly disfigure the 

 specimen when dried. The exterior should then be thoroughly scrubbed 

 with a soft tooth or nail-brush. When perfectly clean, inside and out, the 

 water should be carefully emptied out and the shell put aside in the air, 

 but not in*the sun, to dry. No oil or acid should be used on any of the land 

 shells. It is not desirable to attempt to clean the small species by removing 

 the animals. By keeping them for a short time in a dry place, the animal 

 will retire far within the shell. Then they should be put into 25 per cent, 

 alcohol for a day or two. If to be left longer in the alcohol, the strength 



