oO) 
FXG) 
PALEOZOIC PALEONTOLOGY. 
rarely a little concave just in front of the hinge-line; the anterior 
margin regularly rounded. Pedicle valve convex, broadly subcarinate 
along the mesial line, from which the surface slopes to the lateral 
margins with a flattened convex curve; beak small; cardinal area 
rather narrow, its margins subparallel. Brachial valve nearly flat, 
or slightly concave, often with a narrow mesial sinus which becomes 
more conspicuous anteriorly. Surface of each valve marked by from 
eighteen to twenty, broad, simple, rounded plications, the median one 
on the pedicle valve being broader and more elevated than the others, 
with a corresponding broader furrow along the median line of the 
brachial valve. The plications are crossed by fine, concentric striz, 
and by a few stronger, imbricating, lamellose lines of growth. 
The dimensions of the best of the New Jersey specimens are: 
length, 14 mm.; width, 11 mm. 
Remarks.—The New Jersey specimens are all badly crushed and 
distorted, but some are sufficiently well-preserved to make the certain 
identification of the species possible. 
SPIRIFER AUDACULUS (Con.).? 
Plate LIII., Fig. 1. 
1867. Sgirifer medialis Hall, Pal. N. Y., vol. IV., p. 227, pli 33) 
figs. 1-25, pl. 38*, figs. 1-11. ie 
Description.—A few small, distorted, more or less imperfect speci- 
mens of a species of Spirifer from the outlet of the Oak Ridge reservoir 
seem to be referable to this common species of the New York Hamilton 
formation. The pedicle valve has a rather high, more or less concave 
cardinal area, with a moderately-incurved beak; the mesial sinus is 
sharply defined, angular toward the beak, becoming rounded anteriorly 
and is without plications; each lateral slope is marked by fifteen or 
sixteen simple plications. The brachial valve is less convex than the 
pedicle, with a well-defined mesial fold and with plications similar 
to those upon the opposite valve. The width of the largest and best- 
preserved specimen which has been observed in the collections is 19 
mm. along the hinge-line, which is the widest portion of the shell. 
Remarks.—Although the New Jersey specimens of this shell are all 
smaller than full-grown specimens from the Hamilton formation of 
New York, it is believed that they are specifically identical with them. 
