DEVONIAN FAUNAS. 390 
MEGAMBONIA PARVA Tf. Sp. 
Plate XLIII., Fig. 12. 
Description——Shell small, oblique; hinge-line straight, about 
three-fourths the total length of the shell; both cardinal extremities 
rounded. Posterior, basal and lower portion of the anterior margin 
regularly rounded; a little below the middle the anterior margin is 
sinuate and above the sinus it is convexly-curved to the anterior ex- 
tremity of the hinge-line. Left valve strongly convex, the beak 
prominent and projecting beyond the hinge-line, situated at about 
the anterior third of the shell. Posterior umbonal slope concave, the 
posterior wing not sharply separated from the body of the shell. 
Anterior wing convex, separated from the body of the shell by a 
rounded sinus, which extends towards the beak from the sinuosity in 
the anterior margin; in front of this sinus is a rounded fold, the 
anterior slope of which is slightly concave. Surface marked by 
fine, radiating coste, about four or five in the space of 1 mm., which 
on the body of the shell are flat-topped and broader than the inter- 
vening furrows, and bear two or three very fine longitudinal strie. 
On the wings the radiating coste are narrower and sharper, being 
much narrower than the intervening furrows. The radiating 
markings are crossed by finer concentric lines, which are incon- 
spicuous upon the body of the shell, but which become sublamellose 
between the cost upon the wings, more especially upon the posterior 
wing. Toward the beak the surface markings resemble those of 
the posterior wing rather than those of the body of the shell below. 
The dimensions of a nearly-perfect left valve are: length, 10.5 
mm.; height, 10 mm.; convexity, 5 mm. 
Remarks.—This shell resembles M. crenistriata Clarke, from the 
Oriskany beds of Becraft mountain, but is smaller, with a straighter 
hinge-line and with quite different surface markings. 
MEGAMBONIA? sp. undet. 
A single fragmentary specimen of a pelecypod shell resembles some- 
what the illustrations of M. lamellosa Hall, except in being a diminu- 
tive shell, the total length of the specimen not having been more than 14 
