LYMNZIDA OF NORTH AMERICA. 315 
the American shells. It may be noted in passing, that until some Euro- 
pean author revises the nomenclature of the European varieties and 
so called species it will be absolutely impossible to make any intellig- 
ible comparisons. The tendency of some of the students of fresh- 
water shells is to make every mutation a species or variety. A similar 
course practiced on our American palustris would produce several 
hundred of these “species.” 
Galba palustris alpenensis Nov. Var. . Plate XXXIII, figures 
26-33. 
Lymnea palustris BAKER, Trans. Acad. Sci. St. Louis, XVI, p. 10, 1906 
(part). 
Lymnea palustris michiganensis BAKER, Trans. St. Louis Acad. Sei, XVI, 
p. 12, 1906. 
SHELL: Elongated, narrow, very solid; periostracum light horn- 
colored; sculpture as in palustris; whorls six to seven, well rounded, 
the body whorl somewhat obese; spire long and acutely conical, usually 
considerably longer than the aperture; sutures well impressed; aper- 
ture regularly oval; outer lip thickened internally by a well marked 
varix; inner lip rather wide, reflected over the umbilical region, either 
completely closing the perforation or else leaving a very small chink; 
the parietal callus heavy, producing a continuous aperture in many 
specimens ; there is in some specimens a more or less distinctly marked 
plait, but the majority of specimens are without a distinct columellar 
plait, though the axis is distinctly twisted. 
Length. Breadth. Aperture length. Breadth. 
24.25 10.50 11.00 5.50 mill. Type 
23.00 10.00 10.50 ye % 
22.00 10.00 10.00 5.00 ~ " 
19.75 9.00 9.50 AO) a 
21.00 10.00 10.50 5.00 “ © 
16.25 8.00 9.00 A Oe oa 
Types: Chicago Academy of Sciences, eight specimens, No. 23486. 
Tyre Locariry: Thunder Bay Island, near Alpena, Alpena Co., 
Michigan. 
ANIMAL, JAW, RADULA and GENITALIA: Unknown. 
RANGE: Michigan. A race of the Canadian region. 
RECORDS. 
MicuicAn: Thunder Bay Island; Long Lake; Whitefish Point; Sugar 
Island, all near Alpena, Alpena Co. (Nason). 
GEOLOGICAL DISTRIBUTION: Unknown. 
Ecotocy: This race lives on an exposed shore in pools on lime- 
stone ledges where the waters of Lake Huron dash in, producing a 
