A SNAIL. 



Phylum XI, MOLLUSCA; class 3, GASTROPODA; sub-class 2, 

 EUTHYNEURA; order 2, PULMONATA. 



HABITAT. The most common of our snails in the middle West are 

 the fresh-water forms found in ponds, stock tanks, and running streams. 

 The species are all comparatively small, and, in fact, the same may be 

 said of our terrestrial species. We should look for the latter in damp 

 situations under boards and stones or the bark of decaying logs. In the 

 eastern part of our country and in Europe larger species occur some of 

 which are used for food. 



Technical Note. By scraping the sides of "watering troughs with a large 

 dipper having a per /orated bottom, or by dredging in ponds with an 

 insect net one may easily obtain a supply of snails. If placed in 

 aquaria containing alga or other growing plant life they may be kept 

 indefinitely. They can then be transferred to a tumbler or to a shallow 

 glass dish when wanted for study. With the aid of a hand lens you 

 should be able to make out all the details of structure indicated in this 

 exercise. Specimens may be killed in an expanded condition by plac- 

 ing them for a few hours in a tightly corked flask of water that has 

 been allowed to cool after boiling for some time to exclude the air. 



MOVEMENTS. Note the snail's method and rate of progress. 

 Though proverbially slow, it moves faster than its relative the clam. 

 Does the direction in which it moves indicate a head end ? Would you 

 characterize the movement as creeping, crawling, gliding, or swim- 

 ming ? Touch the animal with a pencil or stick and note results. 

 Some of the specimens in the aquarium will probably be found floating 

 on the surface of the water or clinging to the glass at its edge. Disturb 

 one of these and observe how it sinks to the bottom. How was it able 

 to remain afloat? Did you notice a bubble of air escaping as it 

 descended ? Can it rise to the surface again ? 



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