NATURE'S CALENDAR ,5^, 



out, make very pretty objects for a cabi- lyj j^ 



net, for they exist in great variety and 



witii elegant markings. These, living in 

 still waters, are very fragile, but in rapid 

 streams, especially of the southern AUe- 

 ghenian region, where limestone rocks are 

 common, may be gathered scores of differ- 

 ent kinds of spiral snails, called melanians, 

 which are thick- shelled, and often most 

 curiously knobbed and sculptured. All are 

 vegetable feeders, rasping off the surfaces 

 of plants for food, and cleaning the stones 

 of the minute green " moss " which gathers 

 upon them where the current is not too 

 swift ; and they are in their turn eaten by 

 fishes, turtles, and water-birds, though 

 some of the angular melanians must be 

 pretty hard either to crush or swallow. 



Though these live in the water they 

 breathe air, and have a lung-like arrange- 

 ment similar to that of the land snails. 

 These latter are hard to find during the 

 dry, hot, midsummer weather, because 

 this affects them almost as much as does 

 the cold of January, causing them to hide 

 in some damp and shady retreat, and go 

 into a sort of drought torpor, called aesti- 

 vation. To effect this they form a drum- 

 head of hardened slime across the open- 

 ing of the shell, just as we saw them 

 doing in hibernation, and remain quiet 

 until autumn, except when a long rain 

 irwduces them to venture forth. 



Another sort of mollusk, represented 

 by very few species north of Pennsyl- 



July 13 



