254: THE CHICAGO ACADEMY OF SCIENCES. 



hitherto unnoticed. Young specimens of parva are similar to dalli, 

 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, 



Limn&a (Leptolimncea) pilsbryi HEMPHILL, Nautilus, IV, p. 25, June, 1890. 

 Limnaa pilsbryi KEEP, West Amer. Shells, pp. 149, 314, 1904. 

 SHELL: Elongated, narrow, somewhat solid; periostracum light 

 horn colored ; surface sculpture of fine growth lines without spiral lines ; 

 w T horls 6-6 J^, 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 LOCALITY : Fish Spring, Nye County, Nevada. 

 ANIMAL, JAW, RADULA and GENITALIA: Unknown. 

 RANGE : Nevada. A species of the Great Basin region. 



RECORDS. 



NEVADA: Fish Springs, Nye Co., in approximately lat. 38.45, long. 116.30 

 (Hemphill). 



GEOLOGICAL DISTRIBUTION : Unknown. 



ECOLOGY: Not recorded. 



REMARKS: Pilsbryi is one of the most distinctive of American 

 Lymnaeas, being unlike any other species. Its affinities seem to be 

 with obrussa, the whorls of the spire resembling closely those of Galba 

 ozvascoensis. The cylindrical shell, shouldered whorls, with their deep 

 sutures and the small, oblique aperture, will at once distinguish pilsbryi 

 from any other species. It was at first placed in the subgenus Lepto- 

 limncea, but a comparison with Galba glabra (Miiller), 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.) 



