10 



ILLINOIS STATE GEOLOGICAL SURVEY 



crossed by numerous very fine incised spiral 

 lines; sutures deeply impressed; whorls 5y 2 , 

 convex, the last rapidly enlarging and equal- 

 ling all the others combined; spire elevated, 

 broadly conic; epiconch or nucleus small, 

 round, without striae, reddish brown; aper- 

 ture broadly rounded-ovate, narrowed above ; 

 peristome continuous, rounded, simple, thick- 

 ened a little on the inside, bordered all around 

 with yellowish; inner lip appressed to the 

 columellar [body] wall, thickened at the 

 edge; the base may be imperforate or there 

 may be a small umbilical chink." 



Length, 10.8; diameter, 6.7; aperture 

 length, 5.4; diameter, 3.9 mm. (Measure- 

 ments are mine; Baker gave none for this 

 paratype.) 



Locality of paratype: Southwest corner of 

 Michigan Boulevard and Walton Place, 

 Chicago, Cook County, Illinois. 



Collector: Alvin R. Cahn, date unknown. 



Age designation: Late Wisconsin. 



Remarks: The notations concerning color 

 were based on the shells from living snails, 

 but the shells from the late Wisconsin de- 

 posits in Chicago still retain much of their 

 color. 



Carychium perexiguum Baker, 1938 

 Plate 1, figure 1 



Holotype: Cat. no. P6776, ISGS. 



Original description: Nautilus, v. 51, p. 

 128, April 1938. 



"Shell shorter and more solid than that 

 of exiguum, the sutures more deeply im- 

 pressed and whorls rounder, sometimes shoul- 

 dered at the upper part. Whorls 5, the apical 

 whorls somewhat smaller than in exiguum. 

 Aperture a trifle more than one third of the 

 length of the shell. Margin of aperture with 

 thickened, callus-like lip extending basally to 

 the parietal callus, which is well marked. 

 There is a conspicuous callosity just above 

 the middle of the outer lip. Umbilical re- 

 gion closed by the thickened basal lip. La- 

 mella on columella conspicuous, tubercular, 

 the fold extending upward spirally within 

 the whorls much as in exiguum but it is nar- 

 rower and bent upward over the axis in 

 front. Lower lamella inconspicuous but 

 heavier than in exiguum. Length, 1.8; diam- 

 eter 8.5 [sic for 0.85] mm. Holotype." 



Type locality: Rexroad Ranch, SW*4 

 sec. 22, T. 33 S., R. 29 W., Meade County, 

 Kansas. 



PLATE 1 



Carychium perexiguum Baker, holotype, cat. no. P6776, ISGS: Rexroad Ranch, SWJ4 sec. 22, T. 

 33 S., R. 29 W., Meade County, Kansas, Enlarged 7.2 times. 



Vertigo gouldii loessensis Baker, holotype, cat. no. P2366, ISGS; 33^ miles west, 1% miles south of 

 Lewistown, Fulton County, Illinois. Enlarged 10 times. 



Vertigo hibbardi Baker, holotype, cat. no. P6773, ISGS; Rexroad Ranch, SW34 sec. 22, T. 33 S., 

 R. 29 W., Meade County, Kansas. Enlarged 10 times. 

 5, 6. Strobilops sparsicostata Baker, holotype, cat. no. P6774, ISGS; spiral, basal and apertural views, 

 respectively; Rexroad Ranch, SW}4 sec. 22, T. 33 S., R. 29 W., Meade County, Kansas. Enlarged 

 8.9 times. 



Pomatiopsis scalaris Baker, holotype, cat. no. P2321, ISGS; New Harmony, Posey County, Indiana. 

 Enlarged 3.8 times. 



Amnicola precursor Baker, holotype, cat. no. Z22508, ISGS; Green Lake, off Sherwood Forest Hotel, 

 Green Lake County, Wisconsin. Enlarged 8.4 times. 



Amnicola greenensis Baker, paratype, cat. no. Z16222, ISGS; Green Lake, off Sherwood Forest 

 Hotel, Green Lake County, Wisconsin. Enlarged 4 times. 



Amnicola winkleyi leightoni Baker, holotype, cat. no. P598, ISGS; Rush Lake, Logan County, Ohio. 

 Succinea ovalis pleistocenica Baker, holotype, cat. no. 2088A, ISGS; 3 miles southwest of Marshall, 

 Clark County, Illinois. Enlarged 3.8 times. 



Succinea retusa fultonensis Baker, holotype, cat. no. P2368, ISGS; 2^ miles west, % mile south of 

 Lewistown, Fulton County, Illinois. Enlarged 3.8 times. 



Succinea grosvenorii gelida Baker, holotype, cat. no. P875A, ISGS; % mile northwest of railway 

 depot, Irene, Boone County, Illinois. Enlarged 4.1 times. 



Amnicola lustrica gelida Baker, holotype, cat. no P926, ISGS; near Morris, Grundy County, Illi- 

 nois. Enlarged 8 times. 



Fossaria dalli grandis Baker, holotype, cat. no. P972A, ISGS; Fair Grounds, Joliet, Will County, 

 Illinois. Enlarged 8 times. 



Fig. 



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Fig. 



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Figs 



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Fig. 



9. 



Fig. 

 Fig. 



10. 

 11. 



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Fig. 



15. 



