Notes on Cincinnatian Fossil Types 
333 
that it could have been described under three different names by 
the same individual, Miller. One of these so-called species merely 
is due to obliquely vertical compression of the shell in the soft shale 
and in the original Miller collection was represented by numerous 
specimens differing so widely among each other in the location of 
the so-called plications or sulcae that suspicion certainly should 
have been aroused as to the specific value of these features. A 
second one of these so-called species represents merely a specimen 
preserved in soft shale and crushed flat while lying on its side. The 
third specimen was preserved with a limestone matrix filling its 
interior, and this specimen retains not only its original shape but 
part of the shell substance itself. These so-called species were 
described as Modiolopsis sulcata, Modiolopsis corrugata, and Modi- 
olopsis capax. 
For the fourth term, Sedgwickia divaricata, proposed by Hall 
and Whitfield, there is more excuse. The specimen is a much 
younger one than those found ordinarily, and the plications are 
very strongly marked for such a young specimen, presenting a very 
unfamiliar appearance. 
These so-called species are described and figured on the following 
pages in order to put on record what they really are. 
It is probable that the present writer has himself added to this 
list of synonyms by describing a Canadian specimen, very much 
like the Modiolopsis capax of Miller, as Pholadomorpha chamblien- 
sis. 
41. Pholadomorpha divaricata, Hall and Whitefield 
{Plate V, Figs. 3 A, B, C) 
1875. Sedgwickia ? divaricata Hall and Whitfield, Geol. Surv. Ohio, Pal., 2,p.89, 
Plate 2, Fig. 3 
Pholadomorpha pholadiformis divaricata Foerste, Bull. Sci. Lab. Denison 
Univ., 17, p. 279, Plate 2, Fig. H 
The type of Sedgwickia divaricata is preserved in the James 
collection at Chicago University, and is there numbered 1489. It 
was described as found in the shales of the Hudson River (Cincinnati) 
group, at Blanchester, Ohio. The best exposures in the vicinity 
of Blanchester occur about a mile west of town, along the creek 
about a quarter of a mile north of the railroad. Here the upper 
or Blanchester division of the Waynesville member of the Richmond 
is exposed, but the immediately underlying parts of the middle or 
