12 4 
MONOGRAPH OF THE GENUS STROPHIA. 
Fig. 37. 
numerous, twenty-six on the first whirl, are not prominent, are 
quite regular, but not arranged in lines. They are very smooth, not 
furrowed, and just about as wide as 
the interspaces between them. 
Aperture, rather small, a little 
contracted at the entrance. Lower 
tooth small, about .03 high, not as 
long as high, and but slightly elevated, 
and is about central in position. The 
upper tooth is represented by a slight 
protuberance. 
Margin, produced forward about 
as far as the diameter of the shell, 
is very slightly inclined to the right, a 
trifle beyond the diameter of the shell, 
is slightly thickened, measuring about 
.04, and while the posterior portion is 
produced backward into a blunt edge, it is not rolled over. The 
frontal bar is narrow", yet interrupts the striations, which are, however, 
slightly indicated within. 
Color of shell, creamy white, beautifully mottled and flecked 
with yellowish brown and umber, the markings often crossing the 
striations. Within, deep umber brown, paler on the central tooth 
and fading rather abruptly into creamy white on the edge of the 
margin. 
0 0\u jU’iy 
B 
A, Strophia cinerea tracta, front view of 
type. B, Strophia cinerea mutata, front 
view of type 
DIMENSIONS. 
Size of type, 1.05 by .45. Largest specimen, 1.02 by .47 ; 
smallest, .75 by .37. Longest specimen, 1.25 ; shortest, ,75. Greatest 
diameter, .47 ; smallest, .37. 
OBSERVATIONS. 
While the type form preserves its identity, and prevails in 
numbers, tins is one of the most unsettled forms of Strophia that 1 
have seen, as it has developed no less than five distinct forms, besides 
a small percentage of specimens showing complete gradations with 
typical S. cinerea. The forms are as follows : 
No. 1. A long cylindrical form, with the first three whirls equal 
in diameter. Otherwise asm the type. Size 1,25 by .42. 

