LYMNIDZ OF NORTH AMERICA. 397 
Galba nasoni (Baker). Plate XLII, figures 14-17. 
Lymne@a nasoni Baker, Trans. Acad. Sci. St. Louis, XVI, p. 12, pl. 1, figs. 
1-4, May, 1906. 
SHELL: Rather small, globosely inflated, solid; periostracum 
whitish, tinged with purple; surface dull, marked by rather coarse 
growth lines crossed by fine, impressed spiral lines; nuclear whorls 
small, rounded, very wide and low, flattened, dark brown in color; 
(plate XLIX, figure 0) ; whorls four, roundly inflated, tumid, the body 
whorl very large and bulbous; spire much depressed, very broadly 
acute; sutures slightly impressed; aperture broadly ovate, almost 
round in some specimens, sometimes somewhat expanded, rounded 
anteriorly, somewhat acutely angled posteriorly ; outer lip with a bluish- 
white, longitudinal varix bordering its edge; inner lip narrow, ap- 
pressed to the axis, leaving a very small chink and forming a distinct, 
ascending plait on the columella; the inner lip slightly emargins the 
umbilical chink; the callus on the parietal wall is thin; the interior 
of the aperture is brown in color. 
Length. Width. Aperture length. Width. 
10.50 6.75 7.00 4.25 mill. Type. 
9.50 6.00 7.00 axon). 
8.50 6.00 6.25 4.00 “ << 
10.00 6.75 7.00 500) 5 _ 
Types: The Chicago Academy of Sciences, four specimens, No. 
23788. Cotypes, collection [Hlinois State University and Mr. Bryant 
Walker, Detroit, Michigan. 
Type Locatity: Thunder Bay Island, near Alpena, Michigan. 
ANIMAL, JAW, RADULA and GENITALIA: Unknown. 
Rance: Michigan. A species of the Boreal life zone and of the 
Canadian region. 
RECORDS. 
MicuicAN: Thunder Bay Island, near Alpena, Alpena Co., Michigan 
(Nason). 
GEOLOGICAL DIstTRIBUTION: Unknown. 
Ecotocy: Exposed shore of Lake Huron, where the water is 
daily forced into the pools (Nason). 
REMARKS: Nasont may be known by its small size, its short, 
bulbous, dome-shaped spire and wide-spreading aperture. It somewhat 
resembles certain forms of catascopium found in Pine Lake, Charle- 
voix, Michigan, but differs in the very short spire, broad and tumid 
last whorl, and in having one whorl less. The columellar plait is 
also more distinct. Woodruffi has a differently shaped shell and a 
totally different inner lip. Galba apicina is liable to be confused with 
