3t8 ON COLLECTING SHELLS. 



water, where they may find concealment either in grass or under 

 the shade of aquatic plants. 



Among our most minute species are those that delight in wet 

 grass lands, or in localities that are usually moist during a very 

 considerable portion of the year. They are sometimes found in 

 such localities congregated in hundreds under stray fragments 

 of boards, bits of wood, etc. 



As cliffei'ent sections of the country offer constantly varying 

 conditions affecting the habits of land shells, it may be expected 

 that some species that usually are fovind in such stations as have 

 just been indicated may in exceptional instances be found under 

 circumstances where the collector might least hope to discover 

 them. It accordingly^ becomes the collector to be at all times 

 on the alert, and to inspect every kind of station. By doing so, 

 he will often unexpectedly discover desirable species and acquire 

 information respecting their habits, of more value to him than 

 any suggestions that might be conveyed to him by a volume of 

 printed instructions. 



As examples it may be stated that in and around dilapidated 

 buildings, where fragments of brick and mortar cover the ground, 

 large numbers of the smaller species of Helix, Pupa, Carj^chium, 

 etc., will be found. The}^ adhere to the under surface of a piece 

 of porous brick in preference to a fragment of gneiss, limestone 

 or other rock. Also the cavitj^ of a decayed tree or stump, when 

 examined in the early days of spring, will reward the searcher 

 abundantly. Rich harvest may also be frequently gathered by 

 laying boards upon the grass or ground, wetting them previously 

 imless immediately after a rain. In taking them up after a 

 night's exposure large numbers of shells will often be attached 

 to the under surface. 



Fresh-water Shells. While searching for those species of land 

 shells that are found usually near water, the collector will often 

 have his attention drawn to air-breathing mollusks that are 

 properly designated aquatic mollusca. The habits of some 

 species of this class are such that by one unacquainted with them 

 they might be confounded with land-shells. Many of these 

 species have a habit of crawling out of the water, remaining on 

 the moist mud without any inconvenience. They will also some- 

 times be found on the stems and leaves of aquatic plants, or on 

 other projecting substances several inches from the surface of 

 the water. In their habits as a class they are adapted to a wide 

 range of conditions, so that they will be found in lakes, ponds, 

 rivers, canals, ditches, stagnant pools, swamps, and small rivulets, 

 though some species appear to be adapted to a narrow range of 

 conditions ; the class, however, has its representatives over the 

 whole continent. Though by far the greater number of species 

 of mollusca belonging to this class prefer shallow water, feeding 



