LYMNZIDA OF NORTH AMERICA. yd 
a shell is found in the autotypes of desidiosa in the Philadelphia Acad- 
emy and this type of shell occurs in localities in the eastern part of 
the United States, and is easily separable from any other known species 
or variety. The spire varies considerably, being short or long or even 
scalariform. There are from 2 to 5 rest varices on the whorls. 
Desidiosa, then, differs from obrussa (desidiosa of authors) in 
its generally larger and more solid shell, longer and more turreted 
spire, more pronounced and heavier sculpture and more convex whorls, 
with deeper sutures; in having a distinct internal rib inside the outer 
lip and in the presence of a fold on the columella. Compared with 
palustris, desidiosa is smaller, usually more solid and with a more 
obese body-whorl and a more dilated aperture. The spire, too, is more 
sharply conic and the whorls are more tightly coiled, producing a deeper 
suture. The inner lip is also more expanded, producing a heavier 
callus. The shells called elodes by Say are larger, more flat-sided, with 
a longer spire, and the whorls are not so rounded and are more oblique. 
If we accept the evidence afforded by Say’s specimens, and there seems 
to the writer to be no other course, then the shells usually called de- 
sidiosa must bear the name of obrussa, which is the first available name, 
and the name desidiosa must be used for the shells so called by Say. 
There is some variation among the specimens referred to desidiosa, 
especially in the lot from the small stream near the Erie Canal, but 
all have the peculiar pot-bellied aspect of the body whorl, so markedly 
emphasized in Say’s figure (pl. XXXIV, figs. 8-9). Specimens from 
Seneca Lake vary toward palustris alpenensis (pl. XXXIV, figs. 10- 
12). Desidiosa appears to be a depauperate variety of palustris. 
Galba palustris blatchleyi Nov. Var. Plate XXXIII, figures 
34-36. 
Limnea palustris michiganensis BLATCHLEY and DANIELS (non WALKER), 
27 An. Rep. Dept. of Geol and Nat. Res. Ind., 1902, p. 596, 1903 (part).—Dan- 
IELS, |. c., p. 636, 1903 (part). 
SHELL: Elongated, rather solid, periostracum very light-yellowish 
horn; surface polished; sculpture as in palustris; whorls 6 to 6%, 
rounded, the body whorl subglobose; spire acute, longer than the aper- 
ture; sutures well impressed; aperture long-oval; outer lip with heavy 
internal varix; inner lip narrow, triangular, either tightly appressed 
to the columellar region and forming a plait or broadly reflected and 
leaving a narrow chink; axis twisted. 
Length. Breadth. Aperture length. Width. 
20.00 8.00 8.50 4.00 mill. Types 
17.00 8.25 alo 400 “ 3: 
16.50 7.00 8.00 S280 
16.50 7.00 7.60 250) 
