m 
MONOGRAPH OF THE GENUS STROPHIA. 
slightly flattened on top, not furrowed, but smooth, are very regular, 
and of about the same width for their length on each successive 
whirl, and are arranged in lines with scarcely an interruption on each 
line, from the first whirl to the apex. 
Aperture, rather small, arched and about as high as wide, and is 
slightly contracted at the entrance. 
Margin, produced forward about as far as the diameter of the 
shell, is slightly inclined to the right, 
a little beyond the diameter of the shell, 
is thin, about as thick as the shell 
behind it, with the edge smoothly 
rounded. Behind it, the shell is much 
roughened with lines of growth, which, 
on the sides project, showing an incli- 
nation to form a double margin. The 
frontal bar is well developed, protrud- 
ing considerably beyond the striations, 
and is about as thick as the margin. 
Color of shell, dull white through- 
out, pale brown within, becoming paler 
on the margin. 
DIMENSIONS. 
Size of type, 1.50 by .60. Largest specimen, 1.50 by .63 ; 
smallest, 1.15 by .50. Longest specimen, 1.50; shortest, 1.15. Greatest 
diameter, .62 ; smallest, .50. 
OBSERVATIONS. 
As all the specimens of this fine shell that I ever saw were 
occupied by a species of hermit crab, which always smooth away 
any inequality in the shells of which they take possession, the teeth 
w T ere always worn nearly or quite away. J udging from the remains 
of the lower in the type, I should say that it had been large and 
prominent. 
Individual variation is toward a smaller form, 1.15 by .50, with 
eleven whirls, and also toward a form with more widely-apart and less 
regular striations, but all preserve the short upper whirl which is so 
characteristic of this species. In S. glans, S. bimarginator, and 
Fig. 52. 
a b 
Regular Strophia. A, side, B, front view 
of type. 
