644 TRANS. OF THE ACAD. OF SCIENCE. 
width of the shell. Surface ornamented with large concen- 
tric folds, marked with small pits and short longitudinal pli- 
cations. 
Length, .50; breadth, .55 ; thickness, .32. 
This shell very much resembles Spirifer lineatus of Ver- 
neuil, as figured in the Geology of Russia, and 8. perplexa 
of McChesney; but its beak is smaller and its concentric 
folds larger and very differently marked. 
ery abundant in the Chouteau Limestone of Cooper 
county. 
SprriFER VERNONENSIS, n. sp. 
or less p’ 
alate or mucronate extremities ; beak strongly incurved, ty 
scarcely beyond the cardinal border. Surface marked wi 
about eighteen simple rounded plications on each side of the 
mesial fold and sinus; they originate on the beaks and on 
the borders of the area near the beaks; those near the cos 4 
nal extremities are much smaller; it is also ornamented wit 
numerous fine concentric imbricating lamelle, and distinct 
lines of growth. 
Length, 1.12; width, 1.60; thickness, .77. 
From the Chemung rocks of St. Louis county. ‘ 
ariety Ozarkensis is much more angular, sinus tit 
deeply impressed, cardinal extremities more extended, an 
the plications on each side of the mesial fold and sinus are 
often subdivided. 
From the Chemung rocks of Taney county. 
