OF mNISON UNIVERSITY. 
II5 
convexity of the posterior margin. The beak is about one-fourth from 
the anterior extremity. Anterior margin short, oblique, terminating in 
a rather acute angle at the lower margin, which is gently curved. The 
hinge-line is oblique to the axis and nearly straight. The surface is 
quite convex and marked only by concentric lines of growth. 
It is possible that the species is related with Spathella or Modiola 
rather than Leiopteria. A second species or variety is figured on 
Plate V, Fig. 12, of vol. III. This is proportionately more elongate 
and has the lower outline somewhat sinuous at a point near the front 
where a sinus passes over the surface toward the umbo. The poster- 
ior wing is also more strongly extended, yet we suspect these both fall 
in a single species. The first above described form is apparently from 
the highest horizon of Div. Ill, i. e., Keokuk or upper Burlington, 
while the latter is from a lower zone in the same division at Newark. 
Comparative measurements may be taken from the figures as the speci- 
mens are not now available. 
AVICULA? RECTA, sp. n. 
(Plate X, Fig. 13.) 
Shell scarcely oblique, broad and flat, expanded below ; hinge 
about one-half the height; posterior wing small, obscurely rounded, 
posterior margin nearly straight, forming an angle of about 15° with 
the hinge ; anterior wing large, nearly rectangular, separated from the 
body by a depression forming an angle of 45° with the hinge, anterior 
outline with a shallow sinus at the juncture of the ear and body; front 
margin broadly elliptical. The surface is marked by strong, unequal, 
concentric grooves and striae. Length of hinge, 6.5 mm.; height, 12 
mm.; greatest length 10 mm. 
Cuyahoga shales at Cuyahoga Falls, 30 feet below the conglomer- 
ate. 
SOLENOMYA ?? CUYAHOGENSIS, sp. n. 
(Plate X, Fig. i.) 
Shell minute, resembling in most ascertainable characters S. ano- 
dontoides of the coal-measures, but less expanded posteriorly. This 
may prove to be a young specimen of an Edmondia. I will not give 
a formal description but refer to the figure for all known details. 
Length, 6 mm.; height, 3.5 mm. Cuyahoga Falls, 30 feet below the 
conglomerate. 
