126 THE CHICAGO ACADEMY OF SCIENCES. 



Prostate long, narrowly cylindrical, with slightly bulbous ter- 

 mination ; penis thick, about half as long as penis-sac ; lateral teeth 

 tricuspid ; shell succineif orm, axis slightly gyrate. 



Genus Pseudosuccinea Baker. 



Prostate short, pear-shaped when viewed laterally ; penis very 

 slender, longer than penis-sac; first lateral tooth tricuspid, balance 

 bicuspid; shell with depressed spire and large body whorl, the axis 



.gyrate. 



Genus Radix Montfort. 



Prostate very large, irregularly elongate-ovate ; penis very large, 

 one-fourth longer than penis-sac, gradually enlarging in diameter 

 toward the distal end ; lateral teeth tricuspid ; shell large, bulimif orm, 

 highly colored, axis twisted, with a sharp fold. 



Genus Bulimnea Haldeman. 



Prostate large, flatly cylindrical; penis thick, about four-sevenths 



the length of penis-sac ; lateral teeth bicuspid ; the mesocone with a 



distinct entoconic swelling; shell very slender, the apical whorls much 



longer than wide, the whorls very flat-sided; axis gyrate. 



Genus Acella Haldeman. 

 Prostate very large, long-ovate or elongate-pyrif orm ; penis shorter 

 than penis-sac, usually very thick. 



Genus Galba Schrank. 



a. Prostate long-ovate ; penis a trifle shorter than penis-sac, 

 of narrow diameter ; lateral teeth bicuspid ; shell small, usually 

 without spiral sculpture and with a flat, expanded inner lip, 

 without a fold on the columella, the axis being hour-glass shaped. 



Subgenus Galba Schrank. 



b. Genitalia as in (a) ; lateral teeth tricuspid; shell usually 

 small, without strong spiral sculpture; axis as in (a); inner lip 

 not typically expanded as in (a). 



Subgenus Simpsonia Baker. 



c. Prostate elongate-pyriform ; penis from three-fourths to 

 four-fifths the length of penis-sac, very thick ; lateral teeth bicus- 

 pid; shell large, with marked spiral sculpture, the columella 

 strongly plicate. 



Subgenus Stagnicola Swainson. 



d. Shell elongated with cylindrical whorls ; details of animal 

 not recorded. 



Subgenus Leptolimn^a Swainson. 



