14 



ILLINOIS STATE GEOLOGICAL SURVEY 



resemble a miniature Planorbis antrosus and 

 producing a subacute carina on the upper 

 surface of the whorls; base of shell deeply 

 concave, forming a wide, saucer-shaped de- 

 pression and umbilicus; the earlier whorls 

 are carinate on the under side but the last 

 whorl is rounded; the last half of the last 

 whorl is markedly deflected, forming a con- 

 tact with but half of the preceding whorl; 

 aperture roundly ovate, shouldered above, 

 the dorsal margin much produced over the 

 ventral margin, the parietal callus joining 

 the margins and causing the aperture to be 

 continuous. 



"Height at aperture 2.00; greatest diam- 

 eter 4.50 mm. Holotype." 



Type locality: Campus of University of 

 Illinois, Urbana, Champaign County, Illi- 

 nois; marls exposed in excavations for foot- 

 ings of south greenhouse. 



Collector: T. E. Savage. 



Age designation: Early Wisconsin marl. 



Remarks: Three paratypic examples, no. 

 Z10776, are in the ISGS collection, together 

 with many other lots from waterlaid depos- 

 its referred to as Early Wisconsin in age. 



Planorbis campanulata ferrissi Baker, 

 1922 



Helisoma campanulata ferrissi (Baker) 



Plate 3, figures 10-12 



Holotype: Cat. no. P1068A, ISGS. 



Original description: Trans. Illinois Acad. 

 Sci., v. 15, p. 412, 1923. 



"The shells from the Joliet marls are dif- 

 ferent from the recent form of typical cam- 

 panulatus. The whorls are not as high, giv- 

 ing the shell the appearance of having a 

 greater diameter and more whorls. The 



marl form is also smaller on the average and 

 the aperture is not as widely campanulate as 

 in the recent form." 



Whorls 5, height, 4.6; maximum diameter, 

 11.5; minimum diameter, 8.5 mm. (Baker's 

 measurements.) 



Type locality: Fair Grounds at Joliet, sec. 

 11, T. 35 N., R. 9 E., Will County, Illinois, 

 in marl deposits. 



Collector: D. J. Fisher, 1921. 



Age designation: Pleistocene, Late Wis- 

 consin marl. 



Remarks: The ISGS collection has two 

 series of paratypes, both from the type lo- 

 cality: no. PI 068, eight specimens; no. 

 PI 066, eight specimens. 



Planorbis parvus urbanensis Baker, 1919 

 Gyraulus urbanensis (Baker) 



Plate 2, figures 7-9 



Holotype: Cat. no. Z10772, ISGS. 



Original description: Nautilus, v. 32, p. 

 94, pi. VII, figs. 4-6, January 1919. 



"Shell differing from parvus by having a 

 round aperture, the last third of the body 

 whorl being depressed below the general level 

 of the spire, deeper sutures, channelled in 

 most individuals, and a deeper umbilical re- 

 gion. The body whorl has not quite as great 

 transverse diameter as in typical parvus. 

 In parvus, the whorls are typically in the 

 same plane, the aperture is oblong or long 

 ovate and the sutures are impressed but not 

 channelled. The umbilical region is also less 

 impressed and has a 'reamed out' appear- 

 ance. 



"Height at aperture, 1.0; greatest diam- 

 eter, 3.00 mm. Holotype." 



PLATE 3 



Figs. 1, 2, 3. Gyraulus cressmani Baker, holotype, cat. no. P7453, ISGS; spiral, basal, and apertural views, 



respectively; south end of Klamath Lake, Siskiyou County, California. Enlarged 8 times. 

 Figs. 4, 5, 6. Planorbula indianensis Baker, holotype, cat. no. P2833, ISGS; spiral, basal, and apertural 



views, respectively; Uniontown Road, 2 miles southwest of Mt. Vernon, Posey County, Indiana. 



Enlarged 4 times. 

 Figs. 7, 8, 9. Planorbis altissimus Baker, holotype, cat. no. ZI0775, ISGS; spiral, basal, and apertural views, 



respectively; Campus, University of Illinois, Urbana, Champaign County, Illinois. Enlarged 8.8 



times. 

 Figs. 10, 11, 12. Planorbis campanulata ferrissi Baker, holotype, cat. no. P1068A, ISGS; spiral, basal, and 



apertural views, respectively; Fair Grounds, Joliet, sec. 11, T. 35 N., R. 9 E., Will County, Illinois. 



Enlarged 3.2 times. 



