230 The Molluscan Fa7nily Planorhidae 



second labial lamella. Smithii is larger than crassilabris and has a much 

 heavier lip callus. It somewhat resembles indianensis but lacks the axial 

 height of that race and the latter also lacks the lip callus of smithii. 

 Planorhula smithii is named for Herbert H. Smith. 



GENUS Menetus 



Menetus coloradoensis, New Species 



Plate 122, figs. 23-25 



Shell acutely lenticular, flattened, with three whorls. Color blackish brown. 

 A rounded carina on the periphery which is impressed both above and 

 below the periphery a short distance from the edge. The carina is not acute 

 (excepting in immature specimens) but is bluntly rounded. Upper surface 

 flattened, with deeply inpressed sutures. The whorls tumid near the sutures. 

 Base convex near the suture but flattened toward the periphery. Basal 

 whorls separated by deep sutures. Sculpture ranging from coarse growth 

 lines to evenly spaced ribs, spiral lines very fine. Some specimens begin 

 with coarse growth lines and end with ribs. Aperture triangular, upper 

 and lower lips arching downward and upward to meet the periphery which 

 is not sharp but is narrowly rounded. Upper lip projects just above the 

 periphery and is flat, but lower lip has a long columellar region and is 

 convex. Aperture much wider than high, jmrplish within and somewhat 

 pearly. Umbilicus rather wide and deep. 



Shell Greater Lesser Aperture Aperture 



Height Diameter Diameter Height Diameter 



1.0 1.6 Holotype 



0.9 1.8 Paratype 



0.9 1.5 Paratype 



Type Locality. Swamp at head of Eldora Lake, near Eldora, Colorado. 



Type Material. Deposited in the University of Colorado ALiseum, Ac- 

 cession no. 10114. Holotype shown as fig. 25 on plate 122; two paratypes 

 as figs. 23 and 24 on same plate. 



Menetus coloradoensis differs from eracuous in the pinched nature of 

 the periphery, the swollen or tumid base near the suture, and the heavy 

 (in some instances, costate) sculpture. Menetus exacuous megas has a 

 pinched periphery, but in this variety the base and sculpture are as in 

 typical exacuous. The new species is nearest to kansasensis but differs in 

 having a more tumid base and a different type of rib-sculpture. 



Menetus cooper i crassilabris. New Variety 

 Plate 121, figs. 19-21; plate 122, fig. 13; plate 123, fig. 26 



Specimens like cooperi but with heavy callus just within lip. Shell of four 

 whorls. Heavy spiral sculpture. Whorls usually rounded but with slight 

 indication of carina at shoulder as in cooperi. Several spiral ridges below 

 shoulder, and base often malleated as in cooperi. Umbilicus with rounded 

 edges. Aperture rounded, not usually modified by carina. Most shells are 

 smaller than cooperi. 



Shell Greater Lesser Aperture Aperture 



Height Diameter Diameter Height Diameter 

 2.1 5.4 4.0 1.6 2.0 Holotype 



