LATE CENOZOIC GASTROPODS 



13 



tal at the lower part, without peripheral cal- 

 lus; the peristome is thickened in adult 

 specimens. 



"Height 0.50; diameter 2.10; aperture 

 height 0.45 ; diameter .35 mm. Holotype." 



Type locality: Six miles north of Ains- 

 worth, Brown County, Nebraska. 



Collector: Bryan Patterson. 



Age designation: Pleistocene, Kansan. 



Remarks: The Chicago Natural History 

 Museum has para types, no. 26129; other 

 paratypes, no. P6778, ISGS, no. 169948, 

 ANSP. 



Leonard, who found this distinctive spe- 

 cies widely dispersed in Pleistocene deposits 

 of Kansan age, reports (Univ. Kansas Paleo. 

 Contrib., art. 3, Mollusca, p. 20, pi. 3, fig. 

 1, 1950) that adults possess six whorls, and 

 measure 4.0 mm. in diameter. 



Menetus kansasensis Baker, 1938 

 Plate 2, figures 1-3 



Holotype: Cat. no. P6778, ISGS. 



Original description: Nautilus, v. 51, p. 

 129, April 1938. 



"Shell lenticular as in M. exacuous (Say). 

 Periphery carinate with a 'pinched' border as 

 in M. a. Megas [sic] (Dall). Whorls 3%. 

 Umbilicus wide, shallow, the whorls rounding 

 into it. Sculpture consisting of more or less 

 regularly spaced ribs extending from the 

 suture in a backward curve to and over the 

 periphery to the base and into the umbilicus. 

 The ribs may be equally spaced, with strong 

 growth lines between, or they may be so 

 crowded together as to form a continuous 

 series of ribs without intervening spaces. 

 The surface above and below is covered with 

 strong spiral lines. 



"Length 1.0; diameter 5.0 mm. Holo- 

 type." 



Type locality: Rexroad Ranch, SW^4 

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

 Kansas. 



Collector: C. W. Hibbard and party, July 

 1937. 



Age designation: Pleistocene, late Nebras- 

 kan, in Blanco formation. 



Remarks: The ISGS collection contains 



two series of paratypes, no. P6778 and no. 

 P7456. 



Parapholyx packardi corrugata Baker, 

 1942 



Plate 2, figures 16, 17 



Holotype: Cat. no. P7451, ISGS. 



Original description: Nautilus, v. 55, p. 

 132, April 1942. 



"Shell of 3-31/2 whorls, the spire flattened 

 or slightly elevated, the body whorl very 

 large; sutures not well impressed; aperture 

 about as wide as high, rounded above, 

 slightly angulated below; columella thick- 

 ened by a heavy plait parallel with the axis; 

 umbilicus closed or with a slight vertical 

 chink; there is no evidence of a tooth on the 

 columella as described for packardi) sculp- 

 ture of coarse growth lines or of distinct, 

 regular ribs evenly spaced; spiral lines show- 

 ing faintly in some specimens." 



Height, 8.5; maximum diameter, 10.5; 

 lesser diameter, 7.9; aperture height, 7.0; 

 diameter, 6.9 mm. Holotype. (Baker's 

 measurements.) 



Type locality: Near Summer Lake, Lake 

 County, Oregon; well boring at depth of 

 1080 feet. 



Collector: C. L. Huffaker. 



Age designation: Pliocene? 



Remarks: The ISGS collection contains 

 12 paratypic examples, including 5 juvenile 

 shells, no. P7452. 



Planorbis altissimus Baker, 1919 

 Gyraulus altissimus (Baker) 



Plate 3, figures 7-9 



Holotype: Cat. no. Z10775, ISGS. 



Original description: Nautilus, v. 32, p. 

 95, pi. VII, figs. 7-10, January 1919. 



"Shell depressed, with flatly rounded pe- 

 riphery which is placed below the center of 

 the whorl; lines of growth fine, crowded, 

 but surface without spiral ornamentation ; 

 whorls 4, regularly increasing in diameter, 

 sloping flatly to the rounded periphery; spire 

 whorls sunken below the general level of 

 the surface, the whorls forming a rather 

 sharp v-shaped suture, causing the shell to 



