monograph op the genus strophia. 12 
No. -t. A color form nearly white, or with a few pale mottlings, 
otherwise as in the type. 
No. o. Form and size about as in the type, but very dark brown 
Onoughout, with white striations, which are more numerous, bein 
t wen tii-five or more. 
No. 4 is a small form, .75 by .37, wdth nine wdiirls only, but the 
margin is considerably thickened, and the color pale, with few or no 
fleckings. Nos. 1, 2, and 3 are not very common, o instituting about 
thiee per cent, of the whole ; of No. 4 there are about six per ce it. 
No. 5 is the most remarkable of all, being pure ivory white in 
color, externally and internally, with a thickened margin (about .07), 
and open aperture. Striations coarse and flattened, twenty to the first 
whirl. Both teeth are very prominent. Size, 1.00 by .37. This 
form recalls No. 3 of S. cinerea, but is smaller, heavier, and whiter. 
I have foui shells only, and did not three of them show some gradations 
toward form No. 4, I should not hesitate to pronounce it a distinct 
species, as it is very far removed from the type. Further investiga- 
tions in the neighborhood of the type location of S c. tracta may 
reveal a fixed locality for this shell. 
HABITS AND DISTRIBUTION. 
I found the Mottled Strophia quite common in a very restricted 
location on the borders of a field, that is situated nearly on the extreme 
eastern point of Flog Island. Here they were clinging to the grass 
and hci bage, but 1 did not then observe any fixed location for the 
various forms. I should judge that the lorm was of quite recent 
origin, and has not yet become settled. 
33 STROPHIA CINEREA MUTATA Novo. 
Changing Strophia, 
Fig. 37, B, front view. 
DESCRIPTION. 
Sp. Ch. Size, medium. Shell, rather thick. Striations, present. 
Whirls, ten. Examined 100 specimens. 
Form of shell, a pointed cylinder, with the first whirl the largest, 
then each successive whirl is slightly smaller than the one above it, as 
far as the fifth whirl, when the shell slopes gradually to a point, form- 
mg an angle of fifty-seven degrees. The striations are numerous, 
Of 
