230 HINTS FOE COLLECTING. 



old graveyards and ploughed fields. Species of Vertigo 

 (e. g. V. antivertigo and V. Moulinsiana) may be caught by 

 laying traps consisting of pieces of decayed wood and of 

 stones with an uneven base, at the edges of ponds which 

 they frequent. Charpentier, when hunting for Clausilm 

 in the Tyrol, used to take a boy with him for the purpose 

 of moistening with water from a large syringe or squirt 

 the crevices of rocks in which the Clausilia had ensconced 

 themselves during the daytime ; they soon emerged from 

 their retreat, and were transferred to my friend's collec- 

 ting-boxes. Some species may be taken by sweeping the 

 long grass in woods and shady places with a butterfly- 

 net ; and a bagful of decaying leaves, when dried and 

 shaken in a corn- sieve, will yield many of the small 

 Helicid(B and occasionally Acme lineata. Mr. Ashford 

 obtained several of the rare species of Vertigo by 

 sifting and examining the broken twigs, dead leaves, 

 and vegetable mould which accumulate in the fissures 

 of limestone rocks. The rejectamenta of rivers and 

 streams often contain a quantity of dead shells, both 

 land and freshwater, which have been washed away by 

 the rain and carried down by floods. Bogs and pine- 

 forests are more or less unproductive, being apparently 

 distasteful to the snail tribe. The larger freshwater 

 shells, or Unionida, may be procured by a landing-net 

 fixed to a long pole ; the pearl-mussel ( U. margaritifer) , 

 which inhabits shallow rivers and streams, is taken by 

 wading or with a stick cloven at the end. The most 

 useful contrivance for collecting the smaller kinds is a 

 hand-sieve fixed to a short pole or walking-stick, having 

 a ledge or rim about two inches deep and the bottom of 

 fine copper or brass wirework. Aquatic plants can 

 thus be searched, and the mud strained in the water, 

 so as to reap a harvest of Limnaeidae and Sph&riidce. 



