56 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Camarophorella mutabilis n. sp. 
1870. Centronella ? flora A. Winchell, in part, Proc. Amer. phil. soc, vol. 
11, p. 254. 
Type and figured specimens in collection of Eber and J. E. Hvde, 
Lancaster, Ohio, from near the middle of the Waverly series, asso- 
ciated with a mixed Osage-Kinderhook fauna, Sciotoville, Ohio. 
Shells very variable, meristelloid in shape and moderately thick. 
Beak of pedicle valve moderately incurved, not enclosing that of 
brachial valve nor concealing the triangular deltidial plates. Out- 
line transversely elliptical or subcircular, rarely elongate-elliptical 
or ovate, being usually broader than high; in old specimens sometimes 
subpentagonal; greatest breadth near the middle of the brachial 
valve, sometimes distinctly above or below. Fold and sinus present 
in all except very immature forms, often represented in the young 
specimens by a slight flexure on the anterior margin, always distinct 
in the adult but never showing more than a moderate development 
even in old specimens. In adults, fold not noticeable on posterior 
half or two thirds of shell, sinus often more distinct at an earlier stage 
but very shallow. In all specimens showing the exterior, both fold 
and sinus marked by a slightly depressed furrow extending down the 
middle of the valves from the beak to the anterior margin, a feature 
which is present from a very early stage. 
Surface somewhat irregularly marked by fine concentric striae and 
occasional slight wrinkles of growth, crossed by very fine radiating 
striae, eight or ten of which occupy the space of one millimeter; radi- 
ating striae sharply rounded, the flat furrows between being consider- 
ably broader than the ridges. Inner surface of both valves marked 
by radiating furrows of greater or less strength, the impressions of 
vascular sinuses of the mantle, and fine pittings. 
Muscular platforms and septa not essentially different from those 
seen in Camarophorella lenticularis, as far as the latter is known. 
As the characters of specific value of the brachidium of C. mufahilis 
are unknown, it is not necessary to repeat its description. 
It seems well to insert the original description of Camarophorella 
lenticularis at this point in order to bring all that is known of the genus 
into the jiresent paper and the better to facilitate comparison. 
