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monograph of the genus strophia. 
21. STROPHSA INI PLATA. 
Swollen Strophia, 
Plate VII, 21 & 21 a, shell: Fig. 30; a, front, b, left. side. 
DESCRIPTION. 
Sp. Ch. Size, medium. Shell, heavy. Striations are absent. 
Whirls, 10. Teeth, two, and short. Examined 25 specimens. 
Form of shell, cylindrical, with the second 
and third whirls the largest in diameter, the 
first and fourth are a little smaller, the fifth is 
considerably smaller than the fourth, and from 
this, the shell slopes rapidly to a blunt round- 
ed, nearly hemispherical apex, forming a wide 
angle of nearly 90 degrees. The surface is pol- 
ished but is slightly furrowed with lines of 
growth, which are much less prominent on the 
lower whirls. The sutures are shallow, and the 
whirls between them are slightly bulging. 
Aperture, of medium size but open, and measures considerably 
more just within than at the entrance. Lower tooth, very slightly de- 
veloped and is raised by gradual elevation from the surrounding surface. 
It is about .10 long. The upper is situated considerably above, is about 
as prominent, but is more conspicuous within. 
Margin, not produced forward as far as the diameter of the shell 
is inclined slightly backward and a little to the right; it is not thickened 
and the outer portion is produced into a thin but not prominent edge 
which is not rolled downward. The frontal bar is not prominent, being 
interrupted in the middle. 
Color of shell externally, white, conspicuously striped with yellow- 
ish brown that becomes nearly yellow on the lower whirls, and which 
occupies the last two, wholly excluding the white. The margin, frontal 
bar, and teeth are yellowish, and on the lower wall, within the aperture, 
are purplish brown stripes that merge into the universal purplish brown 
of the interior. 
A B 
Fig. 30. 
DIMENSIONS. 
Size of types, .90 by .35. Largest specimen, 1.00 by 37; smallest, 
,90 by .35. Longest specimen, 1.00; shortest, .90. Greatest diameter, 
,37; smallest, .35, 
