344 THE CHICAGO ACADEMY OF SCIENCES. , 



Animal: Similar to that of P. lapidaria. 



Radula: Not examined. 



Distribution: Western New York west to Iowa and Min- 

 nesota, Northern Michigan south to the Ohio River. 



Geological distribution : Pleistocene. 



Habitat: Similar to P. lapidaria, but clinging to stones 

 when in the water. 



Remarks: Cincinnatiensis is more common than lapidaria, 

 at least in the area under consideration. This species may be 

 distinguished from lapidaria by its fewer whorls and more 

 robust shell; the spire is also longer and more attenuated in 

 lapidaria than in the present species. The male shell is much 

 wider than that of the female, the last whorl of the former 

 being much enlarged to accommodate the extraordinarily large 

 verge. The females have rather long and elongated shells. 

 (Compare figures.) This species has been found only at Joliet, 

 in the western region. 



142. Pomatiopsis lapidaria Say, pi. xxx, fig. 33; pi. xxxi, fig. 12. 

 Cyclostoma lapidaria SAY, Journ. Phil. Acad., Vol. I, p. 13, 1817. 

 Paludina histrica SAY, Journ. Phil. Acad., Vol. II, p. 175, 1821. 



Shell: Elongated, turreted; color dark brownish-horn; 

 surface shining, lines of growth crowded, slightly wrinkled, 

 numerous; apex rounded and depressed, two nuclear whorls 

 smooth, polished, horn-colored; spire long-conic, turreted; su- 

 tures very much impressed; whorls six, well rounded; aperture 

 roundly ovate, dark colored inside; peristome thin, continuous, 

 reflected so as to form a rounded rim for the aperture; the last 

 whorl, near the aperture, is almost free from the body-whorl; 

 base of shell rounded; umbilicus round and deep. 



Length, 7.00; width, 3.50; aperture length, 2.00; width, 1.75 mill. (10226.) 

 6.50; " '3.00; " " 2.00; " 1.50 " 



Animal: With a short, broad foot, slightly produced at 

 the anterior outer corners; rounded behind; foot provided with 

 three sinuses, of which one separates the foot into an anterior 

 and a posterior part; above this there is a sinus at right angles 

 with the first, which separates the foot from the body, the up- 

 per fold of which merges into the operculigerous lobe poste- 

 riorly; above this there are two folds, one extending from the 

 lower base of the rostrum to the base of the tentacle, and the 

 other from the former point to and beyond the constricted 

 portion called the neck; rostrum rather long, blunt, containing 



