176 



Cincinnati Society of Natural History. 



GASTROPODA. 



The gastropods were all found in a marl bed ; the latter 

 being very soft, the specimens were very easily worked out, 

 and were perfectly preserved. 



4. IylMN.EA PALUSTRIS, MUller. 



5. Limn^a refeExa Say. Elongate variety. Typical 

 but not common. 



6. Limn^a dksidiosa Say. Rather common. The whorls 

 are rather gibbous, and the aperture in some specimens is 

 rather flaring. In several individuals th^ whorls are much 

 swollen, the spire very short and the aperture of good length. 

 The specimens range in size from five to ten millimeters in 

 length. 



7. Peanorbis campanuutus Say. Common and typical. 

 The recent campajiidatiis is frequently subject to considerable 

 variation in the whorls, they being distorted by showing the 

 whorls above or below the plane of the aperture. Among the 

 fossil campanulatus, twenty in number, not a specimen was 

 thus distorted. The bell-shaped aperture was more spread- 

 ing than usual in some individuals. 



8. Peanorbis bicarinatus Say. Common and typical. 

 All of the specimens are rather small, not exceeding eleven 

 millimeters in greatest diameter. 



9. Peanorbis defeECTus Say. Common and typical. 



10. Physa heterostropha Say. Very common. Varies 

 from the typical heterostropha to a form near gyri?ia. In 

 some individuals the aperture is wide and flaring. The 

 whorls number four and a half in all of the specimens. They 

 do not differ in any particular from individuals of the recent 

 heterostropha. 



11. Physa ancieearia Say. This is a form somewhat 

 between heterostropha and ancillaria. It is obconic in form, 

 the aperture somewhat spreading, and the whorls shouldered 

 and four and one half in number. 



12. Cincinnatia cincinnatiensis Anth. Verycommon. 

 Some specimens approach Amnicola limosa in form, the spire 



