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PLATE 118 . 
Page 
Fig. 1. Strophostylus matheri. 471 
1 a. Profile view of the spire. 
1 b. View of the aperture, which is imperfect in outline, the columellar side being broken off. 
Fig. 2. Strophostylus andrewsi. 472 
2. View of the aperture, columellar lip, etc. The figure does not represent the aperture suf¬ 
ficiently circular. 
Fig. 3-9. Platyceras ventricosum. 475 
3 a, b. Views of a young specimen in which the peristome is not continuous; the body whorl 
encroaching on the aperture, with an attenuated film of the labrum covering it, the lower 
side curving into the umbilicus, and the margin below the volution reflexed nearly pa¬ 
rallel with the axis. In the figure, the labrum is too distinctly shown upon the body 
volution. 
4 & 5. Views of a small specimen of the usual form, with a widely expanded aperture. The 
peristome is only slightly sinuate from the encroachment of the body volution. 
6 a, b. Views of a specimen above the medium size, where the volutions are in contact, the 
peristome free and moderately expanded. 
7 a. A larger specimen in which the peristome is continuous, but joined to the body volution 
and abruptly deflected below, giving the appearance of a columellar lip. The figure re¬ 
presents very imperfectly the extent of the sinuosity and the form of the lip below the 
volution. 
7 b. The upper side of the spire of the same specimen, showing a broad sinuosity in the 
margin. 
8 a, b. Views of the aperture and of the spire of a large individual, where the last volution 
is free, and the peristome continuous and somewhat expanded on the left side. 
9 a, b. The aperture and lower side of a large specimen, where the volutions are contiguous, 
the umbilicus is very small, and the peristome continuous; the outline slightly sinuate 
just below the body volution, and expanded upon that side. 
