278 F. B. Meek—Descriptions of new Silurian Fossils. 
incurved, projecting moderately beyond that of the other valve. 
Surface ornamented by fine marks of growth, and numerous 
minute, distinct, regularly disposed granulations. : 
Length of one of the largest, and most gibbous specimens, 
0°55 inch; breadth of do., 0°50 inch; convexity of same, 0°53 
inch. Other individuals of near the same length and breadth 
in the number and arrangement of the plications, with A. neglecta 
Hall, from New York, Niagara and Clinton groups. But if 
that shell has been correctly figured and described, from well- 
preserved specimens, it must be distinct from this, as there are 
no surface granulations illustrated in the figures or mentioned 
in the description of the New York species; while they are 
quite distinctly and beautifully defined on those before me from 
Ohio ork Niagara fossils are usually found in 
a good state of preservation, it is very improbable that such a 
character could have escaped attention in 2. neglecta. 1 there: 
fore feel strongly inclined to regard the shell under considera- 
tion as a distinct species; but as it agrees so closely in other 
characters with R. neglecta, have concluded to view it, for the 
resent, as a variety of that shell, under the name scobind, 
which can be retained for it should it prove, as I think it will, 
to be a distinct species. a 
It is possible that the internal characters of the species will 
be found to differ generically from those of Rhynchonella, 4 
distinctly prided surface being unusual in that genus. 
Locality and position.—Clinton group, Dayton, Ohio. Found 
by Prof. Orton. 
PLEUROTOMARIA (SCALITES ?) TROPIDOPHORA M. 
