42 THE CHICAGO ACADEMY OF SCIENCES. 



which enter the foot or other outlying parts of the Limnaea proceed 

 no further." 



The genitalia of Galba palustris from Braddocks Bay, N. Y., has 

 been observed to be infested with thousands of a small parasite. These 

 cases were all confined to individuals with malleated shells. It is 

 probable that many of the American Lymnaeas offer hosts for early 

 stages of worms, but this subject does not appear to have been given 

 much attention by American zoologists. 



h. FOOD. 



The normal food of the Lymnaeas is vegetal ; this, however, varies 

 according to circumstances or individual preference. That the family 

 is carnivorous at nearly all times is proven by the following table. 



Deviations of Lymngea from plant food. 1 



Food. 

 Living newt (plenty of plant food accessible). 

 Living Stickleback. 

 Old fish head. 

 An old newspaper. 

 Dead carcasses of dogs, cats, etc. 

 A live leach. 



Plankton caught in mucus trap. 

 Dytiscus larvae, snails, minnows. 



It would appear that many Lymnaeas adopt a flesh diet from 

 choice. Semper s cites the case of several confined Lymnaeas in which 

 they attacked healthy living specimens of a large water newt (Triton- 

 taniatus) and after overcoming them, devour them with evident relish, 

 although there was an abundance of their favorite vegetable food 

 growing near them. Living minnows have also served as an animal 

 diet by preference. 9 



The vegetable food of Lymnaea consists largely of confervae, the 

 stems of water plants, diatoms, desmids, spirogyra and other pond 

 scums. It is believed by some conchologists 10 that the absence of vege- 

 table food is the cause of the well-known habit in Lymnaea of eating the 

 shell of its fellow captives w T hen in captivity. Air. Walter's remarks 

 on the food of these animals are so pertinent that they are repeated 

 below : 



Authority. 



Species. 



Semper 



stagnalis 



Ullyet 2 



stagnalis 



Cockerell 3 



stagnalis 



Cockerell 4 



stagnalis 



Baker 5 



palustris 



Sterki 6 



palustris 



Brockmeier 7 



peregra 



Cooke 2 



stagnalis 



•After Walter. Cold Spring Harbor Mon., VI. p. 21. 

 2 Cited by Cooke, Moll., p. 34. 

 3 Cooke, p. 37. 



"Science Gossip. 1S83. p. 163. 

 5 Moll. Chi. Area. p. 285. 

 6 Xautilus, V, p. 94. 



7 Forsch.-Ber. Biol. Stat., Plon. Th. 6, p. 165. 

 s Animal life, p. 59. 

 9 Cooke, p. 37. 

 "Clessin, Nach. Mai. Ges., V, p. 28, 1S73. 



