a poards —- 
THE NATURAL HISTORY SURVEY. 273 
central tooth as usual; first four laterals with a quadrate base 
of attachment, about as wide as high; reflection bicuspid, the 
inner cusp very large, the outer cusp smaller; fifth to seventh 
transitory, the inner cusp becoming split up into two cusps 
and asmaller cusp appearing on the outer side of the outer 
cusp; eighth, and all after true marginals, long and narrow, 
with from five to seven cusps; at first two of the cusps are 
situated some distance up the outer margin of the cusp, but 
finally (20) they appear only on the distal end (Fig. 88). 
Genitalia: Not examined. 
Distribution: Same as caperata. 
Geological distribution: Pleistocene; Loess. 
Habitat: Similar to and almost always associated with 
caperaia. 
Remarks: This variety was formerly identified as cudbenszs 
Pfr., but that species has a smooth shell and is more robust, 
grouping with Zwmels and destdiosa rather than with the caperata 
section. Umbilicata is doubtless a form of caperata, but seems 
distinct enough to constitute a separate variety characterized 
by ashort spire and swollen whorls. Like caperata, the variety 
is universally distributed throughout the area, but is not quite 
so common. Fossil specimens have been found in sand banks 
along the lake shore north of Graceland avenue. 
110. Limnzea palustris Miiller, pl. xxxii, fig. 1. 
Limnea palustris MULLER, Zool. Dan. Prodr., 2984, 1776. 
Limneus elodes SAY, Journ. Phil. Acad., Vol. II, p. 169, 1821. 
Limnea umbrosa SAY, Amer. Conch., pl. xxxi, fig. 1, 1832. 
Limnea plebeta GOULD, Invert. of Mass., 1841. 
Limnea fragilis HALDEMAN (non Linné), Mon. p. 20, pl. vi (non figs. 
10, 11), 1842. 
Limne@a sumasst BAIRD, Proc. Zodl. Soc., London, p. 68, 1863. 
Limnea palustris var. zebra J. W. TAYLOR, British Mollusca (vide 
Walker, in letter). 
Shell; Varying from elongate to elongate-ovate, rather 
thin; color varying from pale brown to almost jet black; sur- 
face dull to shining, covered with numerous crowded growth 
lines crossed by several elevated spiral lines and by numerous 
very fine impressed spiral lines, which give the surface a mal- 
leated aspect; the whorls are sometimes encircled by coarse 
wrinkles, and frequently the epidermis is so arranged as to 
show longitudinal stripes of white and horn color, alternating; 
whorls six, rounded, the last varying in its rotundity; spire 
sharp and pointed, varying from over half to three-fifths the 
