central tooth was covered with little cusps, and there were only three 

 teeth on one side, instead of thirty or forty, as in the other snails, 

 and these teeth were long and narrow, the cusps showing as fine 

 serrations at the upper end of the tooth. The Professor told us that 

 many of the water breathers and marine snails 

 possessed a radula with a few teeth on each 

 side of a central tooth. 



Before bringing our work of the evening 

 to a close, we were shown a specimen of a com- 

 mon pond snail in which the mouth was open 

 to its fullest extent, showing the three horny 

 jaws attached to the lips and the radula situ- 



, . , , Mouth parts of pond snail, 



ated lar back in the throat. 1 he r rOieSSOr Said Limnsea reflexa. Prom drowned 



that this was the only specimen he had been able ffiSSS; A o!SdS; J SH& 

 to prepare showing these features so clearly. 



As we were bidding him good night, he asked us if we would like to 

 visit the museum again on the following Saturday and study some 

 of the varieties of land snails. We quickly accepted his kind invita- 

 tion, and promised to meet him at the museum promptly at one o'clock 

 in the afternoon. 



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45 



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