Notes on Cincinnatian Fossil Types 
315 
25. Crania alternata, James 
(Plate III, Figs. 10 A, B 
1879» Crania alternata James, Paleontologist, S, p. 23 
The type of Crania alternata, numbered 1557, is preserved in the 
James collection, at Chicago University. The width of the shell is 
9.5 millimeters; the length, 8 millimeters; and the height, 2.2 milli- 
meters. The upper valve is marked by vertical costae or striations, 
due to the radiating plications of the shell upon which this Crania 
grew. Fine, concentric striae also are present. 
The specimen was found near Blanchester, Ohio, probably in 
the upper or Blanchester division of the Waynesville member of 
the Richmond, and is regarded merely as one of the many specimens 
of Crania scahiosa which give indications of the surface markings 
of the shells upon which they grew. The type consists of an upper 
valve, no longer attached to the shell on which it grew during life, 
but resting upon the upper surface of a rock fragment containing 
traces of the former presence of Leptaena richmondensis, in addition 
to better preserved remains of other fossils. 
Craniae from the Economy member of the Eden Group 
Five species of Crania have been described from the Economy 
member of the Eden group. In their order of publication these 
species are: Crania dyeri, Cr. percarinata, Cr. parallela, Cr. socialis, 
and Cr. albersi. Of these. Crania dyeri is characterized by sharp 
concentric striae, giving the shell an orbiculoid appearance. Crania 
albersi is characterized by sharp, fine, closely set radiating striae. 
This leaves three species. Crania percarinata, Cr. parallela, and 
Cr. socialis which were distinguished originally by features which 
characterized the shells upon which the Cranias rested, rather than 
Cranias themselves, since these features were merely reproduced 
by the Cranias and did not originate with the latter. In searching 
for features which might be regarded as characteristic of the Cranias 
it was discovered that among the types of each of these three so-called 
species there were shells on which granules were present. These 
granules tend to be elongated in a radial direction, somewhat as in 
Crania setigera from the Trenton of Wisconsin, Iowa, and Minnesota, 
but they are much more minute than in that species. It would be 
easy to combine the three so-called species here discussed into a 
single species characterized by the presence of very minute, radially 
