20 



ILLINOIS STATE GEOLOGICAL SURVEY 



"Height, 8.1; diameter, 4.0; aperture 

 height, 5.0; diameter, 2.8 mm. Holotype." 



Type locality: Two and 1/4 miles west and 

 % miles south of Lewistown, Fulton County, 

 Illinois. 



Collector: H. R. Wanless, summer, 1927. 



Age designation: Pleistocene, Early Wis- 

 consin, gray silts. 



Remarks: Two paratypes from the type 

 locality, and bearing the same number as the 

 holotype, are in the ISGS collection; other 

 paratypes, no. 145109, ANSP. Other lots 

 are found in the ISGS collection, but the 

 snail is not common in Pleistocene deposits 

 of Illinois. 



Valvata lewisii precursor Baker, 1928 

 Plate 4, figure 2 



Holotype: Cat. no. P2360, ISGS. 



Original description: Nautilus, v. 41, p. 

 136-137, April 1922. 



"Shell somewhat larger than lewisii, spire 

 elevated, scalariform, the sutures deeply im- 

 pressed, the whorls notably rounded and set 

 one above another in turban fashion; whorls 

 rather more than four with four full coils 

 visible in front view, the upper two whorls 

 projecting well above each other; the body 

 whorl high, increasing in diameter as it ap- 

 proaches the aperture ; umbilicus wide, deep ; 

 aperture large, rounded, entire, the inner 

 lip only touching the parietal wall; sculp- 

 ture of rather distinct, longitudinal lines of 

 growth resembling tightly wound thread. 



"Height, 4.3 ; diameter, 5.0 mm. Holo- 

 type." 



Type locality: Two and % miles south, 

 one mile west of Lewistown, Fulton County, 

 Illinois. 



Collector: H. R. Wanless, summer, 1927. 



Age designation: Pleistocene, Early Wis- 

 consin, upper gray silts. 



Remarks: The ISGS collection contains 

 paratypes from the type locality, no. P2360, 

 and several lots from various localities iden- 

 tified by Baker as V . I. precursor. The sub- 

 species is not common in Pleistocene deposits 

 in Illinois. Paratypes no. 144923, ANSP. 



Valvata sincera illinoisensis Baker, 

 1929 



Plate 4, figure 1 



Holotype: Cat. no. P1671A, ISGS. 



Original description: Trans. Illinois Acad. 

 Sci., v. 22, p. 189, figure 1, 1929. 



"In the Mollusca of Wisconsin a form of 

 Valvata was referred to sincera danielsi 

 Walker. The receipt of a large collection of 

 Pleistocene fossils from the Illinois Geo- 

 logical Survey indicates that this reference 

 was erroneous. The fossil form is about half 

 the size of danielsi and is apparently wholly 

 extinct. It is a common species in the Pleis- 

 tocene of Illinois and occurs more rarely in 

 Late Wisconsin deposits in Wisconsin. The 

 type locality is near the west end of Crystal 

 Lake, McHenry County, Illinois, in a marl 

 deposit of Late Wisconsin age. This variety 

 does not occur in the Chicago deposits. It is 

 probably the ancestor of both sincera and 

 danielsi, but is nearer sincera." 



Length, 2.7 ; diameter, 2.0 ; length of aper- 

 ture, 1.2; diameter of aperture, 1.1 mm. 

 (Measurements are mine; Baker gave no 

 measurements.) 



Type locality: West end Crystal Lake, 

 McHenry County, Illinois, in marl deposit. 



Collector: M. M. Leighton and E. P. 

 Rothrock, 10 August 1922. 



Age designation: Pleistocene. 



Remarks: Three paratypes from the type 

 locality and bearing the same number as the 

 holotype, are in the ISGS collection; other 

 lots from Illinois are not numerous. 



In the original description, Baker used the 

 heading "new variety," but the figures that 

 accompany the description are labeled Val- 

 vata illinoisensis. As it seemed to be Baker's 

 intention to describe this fossil as a subspe- 

 cies of Valvata sincera, it seems best, for the 

 present at least, to regard illinoisensis as a 

 subspecific name. 



Valvata tricarinata supracarinata 

 Baker, 1921 



Plate 4, figure 3 



Holotype: Cat. no. P928, ISGS. 



