414 ILLINOIS STATE ACADEMY OF SCIENCE 



Comity it seems to have a rather wide distribution. Not 

 3^et reported in the recent fauna. 



Ferrissia parallela (Hald.). Rare, but one specimen 

 found. 



Lymnaea stagnalis appressa Say. The rather pLOor- 

 ly preserved material shows that this large Lymnaea was 

 of good size as compared with the same species in the 

 recent fauna. All of the specimens exhibit a peculiar 

 malleation of the surface not seen in recent specimens. 

 Two pieces of a large shell had this malleation so marked 

 that it was at first identified as Bulimnea magasoma 

 (Say). The presence of this marking on undoubted speci- 

 mens of appressa indicates that this species also may 

 bear these markings that are common on shells living in 

 colder regions than the Chicago of today. 



Acella haldemani (Desh. 'Biiiney). Four undoubted 

 specimens of this somewhat rare Lymnaeid are in the 

 Joliet collection. Compared with the recent form they 

 are much smaller and the aperture is narrower. Halde- 

 mani is known in Illinois only from Cedar Lake, Lake 

 Couiitv, where it is rare. (Baker, Bull., State Lab. Nat. 

 Hist., Vol. VII, p. 103, 1906.) 



Galba caperata (Saj"). A single specimen from the 



marl is smaller than most recent specimens. The spire is 



■ longer than in specimens now living in the same region. 



Galba ohrussa decampi (Streng). Very abundant and 

 variable. Short spired forms of decampi have been re- 

 ferred to galhana. That species, however, has the inner 

 lip turned back over the columella leaving but a small 

 chink and forming, as Say remarked in his diagnosis, 

 ''the sinus of the fold very obvious". Decampi varies 

 from a narrow to a wide shell, but the w^horls are always 

 distinctly shouldered, the umbilicus open, and the colu- 

 mellar lip forming a raised shelf over the umbilicus. De- 

 campi is the common Pleistocene fossil of the central 

 west while g alb an a is comparatively rare. The fossil 

 decampi is much more variable than the form from the 

 recent fauna, Avliich is rare, the spire whorls being more 

 pointed and the sutures deeper. 



