14 Trans. Acad. Sci. of St. Louis. 



It has been confounded with the closely allied species caperata, 

 but is always a wider, more globose shell, and the aperture is 

 generally longer than the spire, while in caperata the spire is 

 always longer than the aperture. In caperata the aperture 

 is elongately ovate while in cubensis it is roundly ovate. The 

 spires of the two species are also quite different. Like cap- 

 erata the present species is universally distributed throughout 

 the area, but is not quite as common. Fossil specimens have 

 been found in the sand banks along the lake shore north of 

 Graceland Avenue. 



7. LiMNAEA PALUSTRis Miiller.* 



PI. I. f. 1, 2. 



Limnaea palustris Miiller, Zool. Dan. Prodr. 2934. 1776. 



Limnaeus elodes Say, Journ. Phil. Acad. 2 : 169. 1821. 



Limnaea umbrosa Say, Amer. Conch, pi. xxxi. f. 1. 1832. 



Limnaea nuttalliana Lea, Proc. Amer. Phil. Soc. 2: 33. 1841. 



Limnaea plebeia Gould, Invert, of Mass. 1841. 



Limnaea expansa Haldeman, Moo. 29. pi. ix. f. 6-8. 1842. 



Limnaea fragilis, Haldeman (non Linn6), Mon. 20. pi. vi. f. 1. 1842. 



Limnaea haydeni Lea, Proc. Phil. Acad. 1858 : 166. 



Limnaea sumassi Baird, Proc. Zool. Soc. London. 68. 1863. 



Limnaea micliiganensis Bryant Walker, The Nautilus. 6 : 33. pi. i. f. 9, 10. 

 1892. (Variety.) 



Limnaeus sufflatus W. W. Calkins, mss. (An expanded form of Halde- 

 man' s expansa.) 



Limnaea intertexta Currier, mss., vide Walker, The Nautilus. 6 : 33. 1892. 



/Shell: Varying from elongate to elongate-ovate, rather 

 thin ; color varying from pale brown to almost jet black ; sur- 

 face dull to shining, covered with numerous crowded growth 

 lines crossed by several elevated spiral lines and by numerous 

 very fine impressed spiral lines, which give the surface a 

 malleated aspect; the whorls are sometimes encircled by 

 coarse wrinkles, and frequently the epidermis is so arranged 

 as to show longitudinal stripes of white and horn color, alter- 

 nating; whorls 6, rounded, the last varying in its rotundity ; 

 spire sharp and pointed, varying from over half to two thirds 

 the length of the entire shell ; sutures well impressed ; aper- 



* It is a grave question whether or not it is wise to make varieties of the 

 numerous forms of this species, as there appears to be no limit to its varia- 

 tion. One may place specimens of this species in a row, beginning with 

 the smaller narrow forms and trace the variation, without a break, to the 

 wide, swollen, typical form. 



