SWALLOW—DESCRIPTION OF FOSSILS. 637 
gularly convex ; associated with the last, in the rocks of Cal- 
laway county. 
STROPHODONTA INFLEXA, 0. sp. 
Shell semiellipsoidal, but a little wider in front, regularly 
arched and coarsely costated. Ventral valve very convex, 
semiellipsoidal, wider in front, highest near the center—re- 
gularly arched to the anterior margin, more abruptly at the 
posterior extremity, and somewhat flattened near the beak— 
Length, 1.41; breadth, 1.21; depth of ventral valve, 83. 
This species most resembles S. cymbiformis ; but it is less 
convex, wider, and is marked with much larger coste—about 
26 on the ventral valve. ‘ 
From the base of the Devonian rocks in Callaway county. 
STROPHODONTA ALTIDORSATA, I. Sp. 
Shell small, very convex, semielliptical, (triangular oe 
young,) auriculate. Ventral valve very convex, much raise 
larly arched towards the anterior pep» Ayedear Hea. 
eak str 7 
in 
ed, projecting a little beyond the cardinal margin; area 
ae 
ears; a crenulated fold marks the straight a otal 
lateral margins turned down, and arched to meet the 
numerous small, rounded, granular, radiating re, 
obsolete, concentric stris, and by a few lamellar era a 
folds ; the radiating plications are increased ay pine ‘ 
