LIMNEA FRAGILIS. 55 



instance had I known that doubts exist as to 

 the shell intended. The figure is from an 

 Oregon specimen alluded to on page 22. A 

 similar one has been recently named L. Nuttalli 

 by Mr. Lea. 



Figure 2 of Plate 15 is a faithful represen- 

 tation of an European shell which has recently 

 made its appearance in our collections, under 

 the name of L. palustris, which I figure for 

 comparison. It differs so much from the nor- 

 mal appearance of this shell, that it is possibly 

 a distinct species, and identical with our L. 

 umbrosa. 



This monograph of the genus Limnea in- 

 cludes all Say's species, together with those of 

 other authors with which I am acquainted. 

 There are, however, some names and descrip- 

 tions of presumed new species, which I cannot 

 identify, and which it will be necessary for 

 their proposers to make known by figures and 

 comparative characters; as, to prevent this 

 work from being interminable, it is not now my 

 intention to recur to genera, which, like the 

 present one, are as nearly finished as my facili- 

 ties permit. 



