138 
Aug. F. Foerste 
they turn from the marginal notch ridge strongly toward the 
apertiiral end for a short distance and then approach the inner 
edge of the whorls at an angle of about 55 degrees. The umbilical 
slopes are steep, departing only about 10 degrees from the vertical. 
The type specimen was found 35 feet below the margin 
of the hill south of Kagawong, on Manitoulin Island, asso- 
ciated with Strophomena sulcata, Strophomena neglecta, and Stro- 
pho7nena kuronensis, near the base of the Richmond section. 
Another specimen was found a short distance southward, at the 
Kagawong Falls. 
Fifteen feet below the base of the Clinton limestone, along 
Elkhorn Creek, 3 miles southeast of Richmond, Indiana, a 
specimen of Helicotoma was found associated with Conocardiwn 
richinondensis , Beatricea undulata, Columnaria alveolata, Colum- 
naria vacua, and some species of Ischyrodonta. In the immedi- 
ately overlying part of the section, 3 feet thick, Ischyrodonta 
decipiens is abundant. Eleven feet below the Clinton, Tetra- 
diu7n and Stro7natocerium occur. Ischyrodonta is seen again at 
7 feet below the Clinton. These strata form the upper part of 
the Elkhorn member of the Richmond, the base occurring 40 
feet below the Clinton, overlying beds containing Strophomena 
vetusta; 15 feet lower, Strophome7ia sulcata, Leptaena richmond- 
ensis, Dinorthis suhquadrata, Rhynchotrema dentata, and other 
Whitewater fossils occur. 
The species of Helicotoma (plate X, Fig. 10; plate XI, Fig. 4), 
found in the Elkhorn member resembles Helicotoma hrocki in the 
steepness of the upper half of the outer side of the whorls ; in the 
marked convexity of the lower half of this side ; and in the flatness 
of the lower side of the whorls, with a moderate concavity length- 
wise on this surface. The character of the surface ornamentation 
of the lower, convex half of the outer surface of the whorls, how- 
ever, could not be determined from the only specimen collected. 
All specimens seen were crushed more or less vertically. None 
were found resembling Helicotoma marginata, Ulrich, described 
from Elkhorn Falls, and evidently from the same locality and 
horizon as the form here illustrated. The type of Helicotoma 
marginata, numbered 45830, is preserved in the U. S. National 
Museum, at Washington. The lateral and umbilical sides of 
the specimen are not exposed. To me, the specimen appeared 
crushed, as though the second last volution had been pushed up 
