THE NATURAL HISTORY SURVEY. 



285 



Geological distribution: Pleistocene; Loess. 



Habitat: Found generally in stagnant spots of ponds and 

 rivers about decaying vegetation. Rotting fruit or vegetables 

 floating in the water will be found a good habitat for this spe- 

 cies. Dredged from a depth of ten meters at High Island 

 Harbor, Lake Michigan. (Vide Bryant Walker.) 



Remarks: This is our largest and finest Limncea, easily 

 distinguished by its great size, pointed spire and ample aper- 

 ture. It varies to a great extent, principally in the form and 

 size of the aperture, which is normally about the same length 

 as the spire, but may be twice its length; it may also be elon- 

 gately rounded or spreading and flaring. With all its variation, 



FIG. 93. 



Radula of LIMN/EA STAGNALIS Linne. (Original.) c, central tooth 

 (abnormal); 1, first lateral; 2, second lateral; 14, fourteenth lateral or first 

 intermediate tooth; 19, 23, marginal teeth. 



however, it is easily identified and cannot be mistaken for any 

 other shell. This species may be classed with palustris, under 

 the remarks on the latter species, in regard to its food. It has 

 been seen about dead carcasses of a number of animals. So 

 far as known it is confined to the southern and western regions. 

 Mr. Bryant Walker has called the writer's attention to the 

 fact that the typical stagnalis of Europe is not found in Amer- 

 ica. A study of numerous specimens has convinced the writer 



