IN A SNAILERY. 19 
and periwinkles (Melania); to quiet brooks for physas and 
coil-shells; for limneas to the reeking swamps and stag- 
nant pools in the wet ooze. I know no better place in the 
world for pond-snails than the tule marshes of the Pacific 
slope, where hundreds of the great graceful Limnea stag- 
nalis lie among the rotting vegetation, or float upside down 
at the surface of the still water. But some of the fresh- 
water mollusks remain most of the time at the bottom, com- 
ing to the surface only to breathe now and then; and to get 
their shells it is necessary to use a sieve-bottomed dipper, or 
THE SNALLS OF THE TORRENTS. 
some sort of dredge. When the water becomes low they 
bury themselves in the mud; it is therefore always profit- 
