642 TRANS. OF THE ACAD. OF SCIENCE. 
ed near the beak, and the others are formed by the successive 
subdivisions of the plications forming the boundaries of the 
sinus; beak large and strongly incurved ; area narrow, lin- 
ear, curved (the extremities towards the dorsal valve) ; 
foramen small, triangular, nearly equilateral. Dorsal valve 
Small specimen—length, .71; width, .95; thickness, 69. 
Large specimen—length, 1.39; width, 1.42; thickness, 1.00. 
This fossil most resembles the S. Marionensis of Dr. Shu- 
mard, but it may be easily distinguished by its curved area, 
large beaks and triangular form. : 
From the Chemung rocks of Pettis county. 
SPIRIFER AMARUS, N. sp. 
Pexty 
angular, arched; cardinal line as long as the width of the 
shell; sinus well defined, simple, deep and regularly con 
eave. Dorsal valve semielliptical, depressed ; beak sm 4 
mesial fold well defined, elevated, round and simple, and but 
little wider than the plications on each side. Surface of ven- 
tral valve marked with five or six simple rounded folds on 
each side of the sinus, and by fine concentric lamellose i 
four or five folds on each side of the mesial fold of dorsa 
valve. 
Length, .22; breadth, .25; height, .15. 
Large Specimen.—Length, .40 ; breadth, 35; height, 28. 
_ This little Spirifer resembles somewhat the §. Anne, but 
it is 
* ' . h 
longer and has fewer plications, the area 1s not - = 
and is more arched, and the mesial fold is not so W! rr 
also has the general appearance of some specimens 
Koninckianus of D’Orbigny. 
