MONOGRAPH OF THE GENUS STROPHIA. 
145 
and polished, and a little more than one half as wide as the inter- 
spaces between them. 
Aperture, rather small, but quite open, and not at all contracted 
at the entrance. Lower tooth, rather prominent, a little elevated, 
about .03 high, and about three times as long as high. There is a 
slight tubercle on the left side between it and the upper tooth. The 
upper tooth is also well developed, and extends further forward than is 
usual, while the space between it and the tubercle is inclined to be 
filled in. 
Margin, not produced as far 
forward as the diameter of the shell, Fig. 45. 
and is placed more nearly central in 
the shell than is usual, and does not 
incline at all to the right, it is a little 
thickened, with the edges beveled and 
produced backward into a blunt edge. 
The frontal bar is not well developed, 
but completely interrupts the stria- 
tions. 
Color of shell, externally, ivory 
white, with a faint bluish tinge, as is 
plainly noticeable in the sutures be- 
tween the whirls ; within it is rather 
pale brown, which color extends over 
the teeth very nearly to the edge of the margin before fading into 
creamy white. 
view, of type. 
DIMENSIONS. 
Size of type, 1.15 by .45. Largest specimen, L32 by .47 ; 
smallest, 1.00 by .45. Greatest diameter, .48 ; smallest, .42. Longest 
specimen, 1.47 ; shortest, 1.03. 
OBSERVATIONS. 
Individual variation in this well-marked and peculiar species is in 
two ways, as follows : 
One is towards a larger, more pointed form and another towards 
one which is shorter. The tubercle on the left side of the central 
tooth is peculiar and marks a tendency which in some specimens 
becomes very prominent and forms a decided double tooth. With this 
double tooth, which appears in about one half the specimens examined, 
