LATE CENOZOIC GASTROPODS 



11 



Collector: C. W. Hibbard and party, sum- 

 mer, 1937. 



Age designation: Pleistocene, late Ne- 

 braskan, in Blanco formation. 



Remarks: Three paratypes, numbered the 

 same as the type, and three paratypic shells, 

 no. P6777, dissected to show structure, are 

 in the ISGS collection. The species is wide- 

 spread in the central Great Plains, where it 

 occurs in Kansan as well as Nebraskan de- 

 posits (Leonard, 1950, Univ. Kansas Paleo. 

 Contrib., Art. 3, Mollusca, p. 1-48). 



A typographical error occurs in the place- 

 ment of the decimal point in the table of 

 measurements given in the original descrip- 

 tion; in all measurements of diameter, the 

 decimal point should be moved one place to 

 the left, that is, 8.5 mm. should read 0.85 



Fossaria dalli grandis Baker, 1930 

 Plate 1, figure 15 



Holotype: Cat. no. P972A, ISGS. 



Original description: Trans. Illinois Acad. 

 Sci., v. 22, p. 427, 1930. 



"The Fossaria dalli of the Pleistocene is 

 uniformly larger, with five to 5% full 

 whorls, the sutures deeper and the whorls 

 rounder, the whole shell wider, the aperture 

 longer and narrower. The type specimen 

 measures: L. 4.5; W. 2.4; Ap. L. 2.3; W. 

 1.3 mm. (No. P372A [sic for P972A], Mus. 

 Nat. Hist., collected by J. H. Ferris from 

 marl beds in the Fair Ground in Joliet, Will 

 Co. Late Wisconsin age). Referable to this 



variety are also specimens from the Yar- 

 mouth interval (Clark Co.), and three de- 

 posits in Late Wisconsin (Carroll, Will, and 

 Whiteside Co.). All are uniformly larger 

 than the recent form, which only rarely at- 

 tains any such proportions in length, and 

 never in width and general size. The recent 

 dalli is undoubtedly the descendant of the 

 larger Pleistocene variety." 



Length, 4.5; width, 2.4; aperture length, 

 2.3; width, 1.3 mm. (Baker's measure- 

 ments.) 



Type locality: Excavation in marl, Fair 

 Grounds, Joliet, Will County, Illinois. 



Collector: J. H. Ferris, 1921. 



Age designation: Pleistocene, Late Wis- 

 consin. 



Remarks: The ISGS collection contains 

 ten paratypic specimens, cat. no. P972B, and 

 many lots from Pleistocene deposits at many 

 different localities. 



Gonyodiscus macclintocki Baker, 1927 

 Discus macclintocki (Baker) 



Plate 2, figures 10-12 



Holotype: Cat. no. P2367, ISGS. 



Original description: Nautilus, v. 41, p. 

 133, April 1927. 



"Shell orbicular, with convex, dome- 

 shaped spire; whorls six, slowly and regu- 

 larly increasing in size, tightly wound, 

 slightly convex, the body whorl typically 

 flatly rounded; sutures well impressed; base 

 flatly rounded, excavated near the widely 

 open umbilicus, which exhibits all of the 



PLATE 2 



Figs. 1, 2, 3. Menetus kansasensis Baker, holotype, cat. no. P6778, ISGS; spiral, basal and apertural views, 



respectively; Rexroad Ranch, SW34 sec. 22, T. 33 S., R. 29 W., Meade County, Kansas. Enlarged 



3.3 times. 

 Figs. 4, 5, 6. Gyraidus pattersoni Baker, holotype, cat. no. 26128, Chicago Natural History Museum; spiral, 



basal, and apertural views, respectively; 6 miles north of Ainsworth, Brown County, Nebraska. 



Enlarged 8 times. 

 Figs. 7, 8, 9. Planorbis parvus urbanensis Baker, holotype, cat. no. Z10772, ISGS; spiral, basal and apertural 



views, respectively; Campus, University of Illinois, Urbana, Champaign County, Illinois. Enlarged 



7.2 times. 

 Figs. 10, 11, 12. Gonyodiscus macclintocki Baker, holotype, cat. no. P2367, ISGS; spiral, basal, and apertural 



views, respectively; 33^ miles east and 1% miles south of Lewistown, Fulton County, Illinois. En- 

 larged 3.2 times. 

 Figs. 13, 14, 15. Gonyodiscus macclintocki angulata Baker, holotype, cat. no. P2359, ISGS; spiral, basal, and 



apertural views, respectively; 4 miles west of bridge, Havana, in Fulton County, Illinois. Enlarged 



3.2 times. 

 Figs. 16, 17. Parapholyx packardi corrugata Baker, holotype, cat. no. P7451, ISGS; spiral and apertural 



views, respectively; well boring, near Summer Lake, Lake County, Oregon. Enlarged 4 times. 



