408 THE CHICAGO ACADEMY OF SCIENCES. 



This species is known only from Berry Lake, in the south- 

 ern region. 



Dr. Sterki reports that among fossils from the lower Loess 

 at Freeport, 111., he found Pisidium virginicum, variabile, com- 

 pressum, fallax, cruciatum, punctatum, walkeri and (?) abditum. 

 Pisidium virginicum, P. abditum and P. compressum have been 

 dredged in Lake Superior at depths ranging from four to four- 

 teen fathoms. 

 162. Limiuea auricularia Linne. Text fig. 138. 



*Limncea auricularia LINNE, Syst. Nat., Ed. XII, p. 1249. 

 Shell: Roundly ovate, inflated, thin; color horny to pale 

 gold; nucleus consisting of one and a half spermaceti-colored, 

 smooth, rapidly increasing whorls; surface shining, lines of 





FIG. 138. 

 LIMN^EA AURICULARIA Linne. Natural size. 



growth fine, wavy, crowded, with occasionally a heavy ridge 

 representing a rest period; whorls four, convex, inflated, the 

 last large and spreading; spire short, conic, very small com- 

 pared with the body whorl; sutures deeply impressed, chan- 

 neled in some specimens; aperture very large, ovate, occupy- 

 ing four-fifths of the length of the entire shell, rounded above 

 and flaring in old specimens below; peristome thin, sharp; 

 columella sigmoid with a plait across the middle, which is 

 reflected over the umbilicus; umbilicus narrow, deep, nearly 

 closed. The epidermis is sometimes marked by light and dark 

 lines of color, alternating. 



Length, 23.00; breadth, 17.00; aperture length, 18.00; breadth, 11.00 mill. 

 20.00; " 15.50; " " 15.50; " 9.50 " 



18.00; " 12.50; " " 13.50; " 8.50 " 



Animal. Body flecked with small white spots on back of 

 head and tentacles, but not on foot; mantle marked by many 



*No attempt has been made to include the synonymy of this species. 



