MONOGRAPH OF THE GENUS STHOPHIA. 
1S1 
Individual variation is considerable ; in one direction it is toward 
a form, with a larger, more rounded orifice ; shells like this are inclined 
to have the upper whirl larger than the others, also all the whirls bulge 
slightly. On the other hand there is a shorter form, with straight 
whirls. A color variation is towards a paler form with the white 
predominating. As the reverse of this, I have a single specimen of a 
beautiful chestnut brown throughout, slightly streaked with creamy. 
This specimen has assumed correlative characters and is thick* r with 
a more contracted orifice, and it is cylindrical in form, the first four 
whirls being equal in character. Besides these variations, which may 
be considered as purely individual, we find the following three well- 
defined forms : 
No. 1. A dwarf form with eight whirls, size, .55 by .30, other- 
wise as in the type. This form is largely represented, at least twenty 
per cent, of the whole number, and I have reasons for believing that 
the tendency of the entire species is in this direction. 
No. 2, a large form, 1.10 by .32. rather cylindrical with the first 
four whirls equal in diameter, with the shell thicker, and the orifice 
large. This form is quite largely represented, but as most of the 
specimens are dead shells, many of which I did not collect, I cannot 
give the exact percentages. The tendency is for this form to pass out 
of existence, or in other words, the species has passed through this 
form and is becoming smaller. 
No. 3 is a singular form, with the first whirl decidedly smaller, 
and the aperture nearly central, disproportionately elongated, consider- 
ably higher than wide and with the first whirl quite small (See fig t 
GO, c). This form is so pronounced that it is quite likely to become 
specific in time. 
This is not the Pupa martensiana of Wienland (See remarks on 
this head under Observations in S. eximea) yet it is so labelled in many 
collections which I have examined. This shell is very thin and fragile, 
so thin, in fact, that the striations can be plainly seen through it, when 
looking in at the aperture. I have never seen any other shell which 
resembles the Strophia agrestina, even belonging to this sub-genus, in 
this respect. The large form of S. agrestina and small specimens of 
S. eximea are alike in size, but differ so utterly, as described, as to be 
at once distinguishable, but the best character, aside from the thinness 
of the shell, in the Grass Strophia, is the absence of the frontal bar, 
this being quite well developed on either side in S. eximea. 
Before closing this article I want to add a few words in regard to 
