INSTRUCTIONS FOR COLLECTING LAND AND 

 FRESH-WATER SHELLS. 



BY DR. JAMES LEWIS, OF MOHAWK, N. Y. 



Explorations. — Before the collector can enter the field with much certainty as 

 to the .luticipated result of his labors, it maybe necessary for him to satisfy him- 

 self that there are in the district about him shells enough to offer encourage- 

 ment. It will be found, generally, that those sections of the country that have 

 a dry sandy soil are unfavorable for the production of molluscs. Regions in 

 which pines abound are proverbially of this character, and here the efforts of the 

 collector are usually but indifferently rewarded. In the moist alluvial soils of 

 limestone formations are found the most favorable conditions for the production 

 of molluscs. This is more notably true with regard to land shells; aquatic 

 species are also affected similarly, but less conspicuously, by the character of the 

 soil. But it will almost invariably be observed that waters deficient in lime do 

 not produce shells as perfect nor in as great numbers as waters charged with this 

 earth. 



Land sJiells. — With a few exceptions, relating to some of the smaller species, 

 and also a few species of semi-aquatic habits, the land shells of this country are 

 found most abundantly in the wooded alluvial regions, where during the day 

 they are concealed under fragments of fallen trees, bits of bark, chips, &c., 

 sometimes concealed under leaves or iu the tufts of rank growths of moss. 

 Some species will be occasionally found in the moist debris of shaly rocks in 

 ravines. Species peculiar to the southern States are sometimes met with on 

 .■ shrubs and trees. But few species living in the northern or central portions ot 

 the country are often so found. Some species of semi-aquatic habits, though 

 occasionally seen on the rank vegetation along rivers, (sometimes several feet 

 from the ground,) are more frequently observed under bits of flood wood, leaves, 

 &c., near the muddy slopes of streams or ponds, or in the vicinity of 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, &c. 



As different sections of the country offer constantly varying conditions affect- 

 ing the habits of land shells, it may be expected that some species that usually 

 are found in such stations as have just been indicated may in exceptional in- 

 stances be found under circumstances where the collector might least expect to 

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

 alert, and to inspect every variety of station. By doing so, he will often unex- 

 pectedly 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 bricks and mortar cover the ground, large numbers of the smaller 

 species of Helix, Pupa, CarycJium, Sec, will be found. They adhere to the un- 

 der surface of a porous brick in preference to a fragment of gneiss, limestone, or 

 other rock. Also the cavity of a decayed tree or stump, when examined in the 



