R54 THE CHICAGO ACADEMY OF SCIENCES. 
hitherto unnoticed. Young specimens of parva are similar to dall, 
but may be distinguished by the less number of whorls in shells of 
the same size and in the different shape of the whorls. The two 
species, parva and dalli, are related, but are easily separated when 
attention is given to the details of size and form. ‘This peculiar little 
species is named in honor of Dr. William H. Dall, curator of the 
division of Mollusks of the Smithsonian Institution. 
Galba pilsbryi (Hemphill). Plate IV, figures A, B. 
Limnea (Leptolimnea) pilsbryi Hempuity, Nautilus, IV, p. 25, June, 1890. 
Limnea pilsbryi Keep, West Amer. Shells, pp. 149, 314, 1904. 
SueLtL: Elongated, narrow, somewhat solid; periostracum light 
horn colored ; surface sculpture of fine growth lines without spiral lines ; 
whorls 6-614, well rounded, slowly increasing in diameter, the body 
whorl much flattened in the middle; spire narrow, attenuated, over 
twice the length of the aperture; the spire whorls are well rounded 
and inclined to be shouldered; sutures deeply indented; aperture long- 
oval, a trifle oblique ; outer lip thin; inner lip narrow, reflexed to form 
a smooth, rounded expansion; parietal callus thin; umbilical chink 
small, slightly emargined by the inner lip; columella smooth, without 
a plait. 
Length. Breadth. Aperture length. Breadth. 
8.00 3.00 2.10 1.10 Type 
Types: Academy of Natural Sciences, Philadelphia, three speci- 
mens, No. 62293. 
Type Locarity: Fish Spring, Nye County, Nevada. 
ANIMAL, JAW, RADULA and GENITALIA: Unknown. 
RANGE: Nevada. A species of the Great Basin region. 
RECORDS. 
NevaApa: Fish Springs, Nye Co., in approximately lat. 38.45, long. 116.30 
(Hemphill). 
GEOLOGICAL DistTRIiBUTION: Unknown. 
Ecotocy: Not recorded. 
Remarks: Pilsbryi is one of the most distinctive of American 
jLymnzas, being unlike any other species. Its affinities seem to be 
with obrussa, the whorls of the spire resembling closely those of Galba 
owascoensis. The cylindrical shell, shouldered whorls, with their deep 
sutures and the small, oblique aperture, will at once distinguish pilsbryt 
trom any other species. It was at first placed in the subgenus Lepto- 
lunnea, but a comparison with Galba glabra (Muller), the type of that 
group, shows that this disposition is not correct, the shape of the whorls 
and especially the inner lip being quite different. (See Plate XLVIII, 
figure 4.) 
