28 Aug. F. Foerste 
Strophomena incurvata is listed also from the Pierce division of 
the Stones Eiver group. 
Strata closely resembling the very fine-grained limestones 
characterizing the High Bridge limestone in central Kentucky, 
occur also in Ontario, along the northern part of Cloche Island, 
along the railroad track, below undoubted Black Biver strata. 
In the absence of fossils, however, their exact equivalency to 
Kentucky or Tennessee strata must remain for future determina- 
tion, although for the present they are regarded as of Lowville 
age. 
Strophomena incurvata makes its first appearance in the Pierce 
limestone of Tennessee. Thence it ranges upward to the base 
of the Carters limestone. Since the lower divisions of the Stones 
River group are not known from the northern part of the Missis- 
sippi basin or from the region bordering the Great Lakes, this 
evidence favors the introduction of Strophomena incurvata from 
some other direction, probably the south or southeast, although 
during late Stones River times and during the deposition of the 
Black River, this species spread to Iowa, Wisconsin, Minnesota, 
Manitoba, and the northern parts of Lake Huron. During the 
deposition of the Black River, it even reached New York and 
Canada. 
The finely striated species of Strophomena, with flabellate mus- 
cular scars in the pedicel valve, typified by Strophomena incur- 
vata, are unknown, in the areas traversed by the Cincinnati 
geanticline, in the Trenton, Eden, and Maysville formations, but 
return in the form of Strophomena neglecta and Strophomena 
planodorsata in the Waynesville and closely related horizons of 
the Richmond. Strophomena planodorsata replaces Strophomena 
neglecta northwestward, in Minnesota and neighboring states, and 
extends southward to western Tennessee. 
Strophomena vicina, Foerste^ 
{Plate VII, Fig. 2, magnified) 
Shells varying from 30 to 35 mm. in width along the hinge-line, 
occasionally attaining a width of 40 mm. The ratio of the width 
to the length usually varies from six-tenths to seven-tenths. 
2 Denison Univ. Bull., vol. xiv, p. 317, Plate VII, Figs. 12 A, B, 1909. 
