O PALUDINA DECISA. 



Tennessee rivers, on the south shore of Lake 

 Michigan, and Mr. R. C. Taylor brought speci- 

 mens from the "Four Lakes" of the North-west 

 Territory. 



OBSERVATIONS. 



The quite young have a very low spire, a 

 globular form, and the aperture very wide, 

 nearly equalling half the entire lower surface 

 in area. The soft parts are semitransparent, 

 without any orange spots. The young are ex- 

 cluded in March, when the shells are 0.14 or 

 0.15 of an inch in length, composed of rather 

 less than three entire whirls. In autumn, pre- 

 vious to the sinking of the animals into the 

 mud to hybernate, the ovaries of the female 

 (extending within the apex of the shell) will be 

 found to contain many young, apparently in as 

 perfect a state as when excluded in the spring. 



Dr. Gould (MS.) states that the shell is 

 bristled with filaments, which are visible when 

 in the water; particularly upon half grown indi- 

 viduals. 



Deshayes does not admit this species in his 

 edition of Lamarck, but places the name (with 

 a question) among the synonyms of P. ponde- 



