PAPERS OX GEOLOGY AND GEOGRAPHY 411 



Distribution of Aquatic Species in Different Localities — Concluded 



Species Morris Joliet Lemont Chicago 



Planorbis campanulaiu 



ferrissi X 



Plauorbis camijanukitus 



Platwrbis arcticus 



Planorbis dejiectu-s X 



Planorbis altissimus X 



Planorbis parvus urbanrnsis 



Ferrissia paralJela 



Lymnaea stagnalis appressa 



AceJIa haldemani 



Galba caperata 



Golba obrussa decampi X 



Galba eJodes jolietensis 



Galba parva 



Galba dain 



G<ilba obrussa exigua 



Total species 10 32 15 24 



The species included in the Ferriss collection are listed 

 below with notes on the critical or interesting species. 

 I am indebted to Dr. V. Sterki, of Xew Philadelphia, 

 Ohio, for the deteiTainations of the Sphaeriidae. 



FRESH- WATER BR'ALVES (PELECYPODS) 



Sphaerium sulcatum (Lam.) Not common. 

 Sphaerium rliomhoideum (Say). Eare. 

 MuscuJium secure (Prime). Common. 

 Pisidium vandb'de Prime. Eare. 

 Pisidium compressum Prime. Common. 

 Pisidium pauperculum Sterki. Abundant. 

 Pisidium miuusculum Sterki. Very rare. 

 Pisidium spleudidulum Sterki. Very rare. 



FRESH-WATER SXAELS (GASTROPODS ) 



Vahata tricarinata (Say). Very abundant and fairly 

 uniform. There is a tendency to lose the middle carina 

 and develop into the variety below. 



Valvata tricarinata perconfusa Walker. Uiicom- 

 mrin. All individuals have the elevated spire and 

 strungiy carinate whorls of tyjDical tricarinata, but the 

 peripheral carina is completely lacking and there are no 

 intergrades, as in tricarinata. 



Valvata lewisii Currier. Eare. but one specimen 

 found. The sx)ire is low and the sculpture very fine. 



