352 THE CHICAGO ACADEMY OF SCIENCES. 



Michigan. Beautiful and typical specimens may be collected 

 at Joliet. 



1453. Valvata bicarinata normalis Walker. Unfigured. 



Valvata bicarinata normalis WALKER, The Nautilus, Vol. XV, p. 125, 

 fig. 5, 1902. 



The shell in the variety differs from bicarinata in being 

 tricarinate, the middle carina very strong and placed on the 

 periphery. The variety occurs at Joliet, 111., and at Miller's, 

 Ind. 



The curious larva case of Phryganea, named by Mr. Lea 

 Valvata arenifera, is found in considerable numbers in various 



A B 



FIG. 132. 



Genitalia of PALUDINA VIVIPARA Linne. (Bronn, Klass. und Ord. 

 der Welch., taf. LXXXVIII, Figs. 5 ($), 6 (tf). A, female; B, male; gal, 

 albuminiparous gland; ov, ovaries; p, penis; rs, receptaculum seminis; t, 

 testicles; ut, uterus; vd, vas deferens; vg, vagina; vs, seminal or genital 

 bladder. 



parts of the region. The case is of exactly the same shape as 

 that of a Valvata, and might be mistaken by an amateur for V. 

 sincera. For a very interesting account of this larva case, see 

 Thos. Bland, Ann. Lye. N. H., Vol. VIII, p. 144. 



FAMILY 



Shell: Globular or conical, either banded or plain and 

 with a greenish epidermis; aperture round; peristome con- 

 tinuous, entire; operculum horny, annular, frequently with a 

 spiral nucleus. 



Animal: With a large, simple foot, and short, simple ros- 

 trum; tentacles short, the right one, in the male, modified to 



