416 ILLINOIS STATE ACADEMY OF SCIENCE 



Polygyra miiJfilineafa algonquinensis Nason. Rare. 

 The small form is the same as the form described by 

 Nason from Algonquin. 



Polygyra multilineata (Say). A rare nmbilicated form. 



Polygyra profunda (Say). Common. Not different 

 from tlie recent form. The "color bands are preserved in 

 some specimens. 



Polygyra albolahtis (Say). Rare. 



From peat deposit near Sag Creek. Collected by J. 

 H. Ferriss. 



LAXD GASTROPODS 



Zonitoides tninuscida (Binney). Rare. 

 Helicodiscws parallelus (Sa}^). Rare. 

 Bifidaria contracta (Say). Rare. 



PULMONATE AQUATIC GASTROPODA 



Lymnaea stagnalis appressa Say. Not common. 



Galha palustris (Miiller). Abundant and variable. 



Galba ohrussa decampi (Streng). Rare. 



Galha ohrussa exigua (Lea). Rare. 



Pliysa gyrina Say. Not common. 



Physa walkeri Crandall. Rare. Spire longer than 

 in tjTDical form. 



Physa Integra hillingsi Heron. Common and va- 

 riable as to height of spire and width of bod}^ whorl. 



Planorhis campanidatus Say. Common. A few 

 specimens approach the form of the Joliet marls called 

 ferrissi. 



Planorhis trivolvis pseudotrivolvis Baker. Com- 

 mon. Very variable in height of whorls. This form 

 seems to be the common large Planorhis of swamps and 

 stagnant pools. It was evidently abundant during 

 Pleistocene times. 



Planorhis antrosus Conrad. Common. In the peat 

 beds the form without spiral striae is the most abundant. 



Planorhis antrosus striatus Baker. Rare. 



Planorhis deflect us Say. Common. The peripheral 

 carina varies from acute to rounded. None of the forms 

 are the hirsutus, however. 



Planorhis altissimus Baker. Not common and not 

 as typical as the form in the Joliet marls. 



