276 THE CHICAGO ACADEMY OF SCIENCES. 
The animal of palustris is very rapid in movement. It 
crawls out of the water and will remain in this position for a 
long time. When crawling, the shell is frequently moved rap- 
idly from side to side, and is carried at all conceivable angles. 
It is a very rapid feeder and will soon clear up the sides of an 
aquarium. Like other species of the genus, palustris has the 
habit of rising very suddenly from the bottom to the top of the 
water where it will then float shell downward. 
110a. Limnza palustris michiganensis Walker, pl. xxxii, fig. 5; pl. xxxi, 
fig. 25. 
Limnea atte michiganensis WALKER, The Nautilus, Vol. VI, p. 33, 
pl. i, figs. 9, 10, 1892. ' 
This form is characterized by the aperture being about 
one-half the total length, the outer lip is thickened within by a 
bluish-white callus edged with brownish black; this shows as 
a white longitudinal band on the outside of the shell; spire 
acute, sutures impressed. Mr. Walker mentions very fine spiral 
lines, but these are as fully developed in the typical forms as 
in thevariety. 
Length, 20.00; width, 8.00; aperture length, 9.00; width, 4.50 mill. (12083.) 
“ 17.00; “ 7.00; « “ 850; © 4,00 “ — (12088.) 
BS ESO Es FSO Os “ y 6.00; 0 (12082.) 
Habitat: Associated with the type, but not as numerous 
in individuals, and found from Michigan to Washington. 
110b. Limnza palustris nutalliana Lea, pl. xxxi, fig. 6. 
Limnea nutalliana LEA, Proc. Amer. Phil. Soc., Vol. II, p. 33, 1841; 
BINNEY, L. & Fr., Wat. Sh. N. A., p. 42, fig. 62, 1865. 
Several specimens apparently referable to this form (which 
would appear to be a good variety of palustris) were collected 
recently by Mr. J. H. Ferriss, at Rock Run, near Joliet. The 
whorls in this species are more swollen and the sutures less 
impressed than in typical palustris. The epidermis is also 
peculiarly banded, the bands showing very plainly in the aper- 
ture. It has been found only at the above locality. 
Length, 20.00; width, 8.50; aperture length, 10.00; width, 5.00 mill. (12843.) 
‘A 18,005. 1%. &* 5:50: “ 4 9.50; 5-500 o> (12aas.) 
Mr. Lea’s description is appended for comparison. 
“Shell ovately conical, rather thin, striate, subdiaphanous, 
pale brown, imperforate; spire rather short; apex red; sutures 
impressed; whorls six, convex; aperture ovate, inflated; banded 
within.” 
The original specimens were from Oregon. 
LVRS hi SS 
