SNAILS OF POND, RIVER AND BROOK. 



Many of my readers have doubtless radula and the operation of eating is not 

 kept an aquarium at some time in their unlike the motions of a cat lapping milk, 

 life and have stocked it with several gold- They are such voracious eaters that the 

 fish, a small turtle and some fresh water dirtiest aquarium will be cleansed by 

 snails. They have also, without doubt, them in a very short time. It is interest- 

 stood in front of the aquarium and ing to note that the young animals 

 watched the strange antics of each of the breathe air through the water for a long 

 three kinds of animals and have won- time, and finally acquire the normal char- 

 dered at the swiftness with which the little acteristic of the family of breathing the 

 snails progressed about the glass sides of air directly. While submerged, the man- 

 the artificial pond. It is of these mol- tie chamber containing the "lung" is 

 luscan denizens of fresh water that I shall tightly closed so that no water can pos- 

 write in this article. sibly get in. It is thought by some that 



In the fresh-water species the shell is the species of Limnaea living at great 



not often rounded like that of the land depths retain the early habit of allowing 



snails, but is more frequently long and the water to fill the mantle cavity and so 



pointed, the spire resembling a church breathe oxygen through the water and 



steeple. The animal, too, differs very are not, therefore, compelled to come to 



greatly, the tentacles being either flat and the surface for air. 



triangular or long and very tapering. The Limnaea lives under many varying 

 eyes are not placed at the end of the eye- conditions, being found in the arctic re- 

 peduncles, as in the land shells, but are gions of Greenland and Iceland as well as 

 generally situated on little swellings at in the tropics, in thermal springs and 

 the base of the tentacles. They may be those containing mineral matter, as sul- 

 found in almost any body of water, ad- phur, as well as in brackish and fresh 

 hering to stones, sticks, and other sub- water. They have been found at a height 

 merged objects, or crawling over the of over fourteen thousand feet in Thibet 

 sandy or muddy bottom. and at a depth of eight hundred feet in 



Our fresh-water snails may be divided Lake Geneva, Switzerland. During 



into two classes ; first, those which times of drought when the streams are 



breathe by means of a lung and which dried up and the surface of the mud is 



must come to the surface at regular in- sun-cracked, the species of this family 



tervals to take in a supply of air, and, sec- bury themselves deeply in the mud and 



ond, those which breathe by means of cover the aperture with an epiphragm, in 



plume-like gills which take the oxygen much the same manner as the land shells, 



directly from the water. This fact accounts for the apparent disap- 



One of the most common and best pearance of all life from a pond when it 



known of the first class is the Limnaeidae, dries up, and its sudden and seemingly 



comprising the pond snails. These ani- unaccountable reappearance when the 



mals have generally a long, graceful shell, pond is again filled with water, 



horn-colored for the most part, but some- A genus of pond snails closely allied 



times greenish without and reddish with- to Limnaea, but having discoidal or 



in the aperture. The animal has a broad, spiral shells, is Flanorbis, the flat-orb 



flat foot, an auriculate or eared head, and shells. Instead of dragging their shells 



flat, triangular tentacles. The habits of after them, as in the last genus, they carry 



these animals are very interesting. They them perfectly perpendicular, or perhaps 



will wander about the sides of an aquar- tilted a little to one side. The animals 



ium, eating the growths of green scum are very rapid in movement, more so than 



which have collected. At this time the Limnaea, which are rather sluggish, 



mouth may be seen to open, exposing the They delight in gliding rapidly about, 



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