I 
424 
PALAEONTOLOGY OF NEW-YORK. 
and Sharpe in the Quarterly Journal of the Geological Society of London, Yol. ii, 
pa. 276, pi. 41; but the general features here shown are apparently common to 
many Spiriferse of the Higher Silurian or Lower Devonian beds. 
Fig. 1 a, b. Dorsal and front views of a specimen in which the shell is partially exfoliated. 
( The mesial fold is more angular in the specimen than is represented in the 
figure.) 
Fig. 1 c. The ventral valve of another specimen, in which the plications are rounded. 
Fig. 1 e. A ventral valve which is more extended on the hinge-line, and preserves to a con¬ 
siderable degree the surface markings, and has about eight plications on each side. 
Fig. 1 f. A ventral valve of proportionally greater length : the plications are broad and 
rounded, and seven are visible on each side. 
Fig. 1 g. Profile view of a gibbous specimen. 
Fig. 1 h. An enlargement of the surface, showing the fine concentric and radiating striae as 
they appear on a worn surface. 
Fig. 2 a. The dorsal side of a cast, in which the plications are sharply angular. 
Fig. 2 b, c, d, e. Casts of the ventral valve, showing a variety of form and markings in the 
cast of the muscular impression, and in the number and development of the 
plications. 
Fig. 2 f. Cardinal view of a cast which is somewhat distorted, and shows a part of the 
ventral valve : the beak is broken off. 
Fig. 2 g. A cardinal view of the cast of a ventral valve, showing the elevation of the process 
filling the beak. 
Fig. 2 h. A similar view, showing also the ventral side and the median line. 
Fig. 2 i. The cast of a distorted specimen. 
Geological position and localities. In the Oriskany sandstone, everywhere in the 
State of New-York, and at Cumberland (Maryland). 
Spirifer intermedins ( n. s.). 
Shell transverse, semielliptical; the ventral valve moderately and re¬ 
gularly convex, area of medium height, foramen large ; mesial sinus 
of moderate depth, rounded. Dorsal valve unknown. 
Surface (of a specimen one and a half inches wide) marked by ten 
depressed plications on each side of the mesial sinus. 
The dental lamellae are not at all or but slightly thickened : the mu- ♦ 
scular impression is broad and strongly striated, with sometimes a filling 
of the cavity of the beak. 
This species has been recognized in a few imperfect specimens of the ventral 
valve; but its regular convexity, more numerous rounded and little elevated pli¬ 
cations, with a somewhat shallow sinus, distinguish it at once from the S. arrectus 
with which it is associated. 
Geological position and locality. In the Oriskany sandstone : Cumberland, Md. 
