and plunged it into a pan of cold water to restore the temper of the 

 steel. Thus we had an excellent tool for extracting the animal from 

 spiral shells. 



Some of the fresh-water snails possessed an operculum, and this we 

 carefully removed from the foot and placed it beside the shell from which 

 the animal was taken. When the shells were perfectly dry, the aperture 

 was filled with cotton, and the operculum fastened to it in its natural 

 position with a little glue. We were told that in some snails the opercu- 

 lum is so large that it curls up when drying, and that such opercula must 

 be placed between two pieces of wood tied tightly together until per- 

 fectly dry. 



Some of the fresh-water snails were covered with incrustations of 

 lime, which we removed with the sharp point of a file, after which a 

 good scrubbing cleaned them very nicely. When dry, the larger fresh- 

 water snails were treated with vaseline in the same manner as the clams, 

 which gave them a fine gloss. 



Professor Parker had accumulated a number of land shells in his 

 snailery, which he asked us to clean for him. These we placed in boil- 

 ing water, extracted the animal, washed the shells thoroughly, and placed 

 them on a board to dry. 



Some slugs had been drowned the day before by placing them in a 

 vessel completely filled with water so as to exclude the air. This killed 

 the animal in an extended position, the eye peduncles and tentacles being 

 stretched out to their fullest extent. Many of the snails had also been 

 treated in this manner. When completely drowned they were removed 

 to alcohol, the strength of which was gradually increased. We asked 

 the Professor how long it took to drown a snail, and he said about twenty- 

 four hours. When we asked how long it took to harden the slugs and 

 snails, he answered by giving us the following formula on a piece of 

 paper: 30 per cent alcohol, 24 hours; 70 per cent alcohol, 30 hours; and 

 85 per cent alcohol for final preservation. He also said that a 1 per cent 

 solution of chromic acid would accomplish the same purpose ; and that 

 the specimen of moderate size might be hardened in about thirty hours, 

 after which it should be thoroughly washed in running water for twenty- 

 four hours, to remove all of the acid. All of these facts we carefully 

 recorded in our note-books, for future reference. 



From some of the slugs we removed the little, flat, internal shell, 

 cleaned and dried them for the cabinet. The very small snails and clams 

 we placed in alcohol for fifteen or twenty minutes, and then dried them. 

 This removed the moisture and prevented any unpleasant odor. 



We asked Professor Parker whether it was necessary to have a differ- 



57 



