56 
more acute on the under side. This difference is more strongly 
contrasted in E. dryope. The umbilicus of the latter is narrower 
with still more abrupt sides. A cross section shows the angle 
of the underside more acute than either E. rotunda or E. supra- 
cingulata , and farther from the margin of the shell. 
Horizon and Locality. Chazyi Aylmer limestone at Mac- 
Laren landing. 
Raphistoma distincta n. sp. 
Plate IV, figures 9, 10, 11 
The shell varies in width from 6 mm. to 22 mm. An average 
specimen is 15 mm. in width, spire 2\ mm., total height 9 mm. 
The low spire consists of three volutions gradually enlarging, 
flat on the top, acute on the peripheral margin, convex below. 
It is noticeable that the larger and older a specimen is, the 
more acute the margin becomes; in some of the older specimens 
the peripheral border is raised. The younger specimens are 
more rounded in every particular. The umbilicus is about a 
third of the width of the shell. It is well defined by the angle 
of the underside of the whorl. In no specimen, however, among 
more than fifty examined, is it entirely free from the matrix. 
In very few specimens is the marking preserved, and always 
but faintly. The striae commence at the suture and pass for- 
ward for about one-third the width of the top of the whorl, 
where they curve back sharply to the peripheral edge. There 
is no specimen showing the striae passing over the margin, but 
on the lower side they again turn forward until the most convex 
portion of the underside of the whorl is reached, where they 
again curve backward and continue down the slope of the um- 
bilicus. 
In general outline and in size and shape of the umbilicus’ 
this species resembles Raphistoma apertum y except that the 
upper surface of the whorl is flat instead of convex near the 
suture line and concave near the periphery, in the more accent- 
uated curves of the striae, which proceed much farther towards 
the lip of shell before they curve backward again. The species 
differs from R. peracutum in having a slight spire and in the 
