900 
PALEONTOLOGY OF NEW-YORK. 
Spirifer condemns (n. s.). 
Plate XXY. Fig. 2 a - i; and Plate XXVIII. Fig. 7. 
Shell semicircular or semielliptical : extremities rounded or salient; 
valves almost equally convex. Ventral valve gibbous towards tlie beak : 
beak more or less elevated above the hinge line, and abruptly incurved 
at the apex : mesial sinus subangular, and produced into an angular 
extension which is much elevated, and sometimes slightly incurved in 
front. Dorsal valve very convex in the centre : beak scarcely incurved; 
mesial elevation obtusely and sometimes acutely angular. Hinge line 
i 
equal to or a little less than the width of the shell. Area of medium 
size, well defined, and extending to the extremities of the hinge line. 
Surface marked by from twelve to fourteen rounded, little elevated, 
simple costte on each side of the mesial lobe and sinus; concentrical¬ 
ly marked by imbricating lamellae, which are striated upon their sur¬ 
faces and granular on the edges. 
In many specimens there are faint indications of a fold on each side of the me¬ 
sial sinus, and of several similar ones upon the corresponding mesial elevation : 
this character, however, is not constant in the specimens examined. 
This species is subject to considerable variation in form, the length and breadth 
being sometimes nearly equal, and the cardinal extremities rounded, while in other 
specimens these are salient. I have seen two specimens only in the shaly limestone; 
the ordinary position of this species being in the Upper Pentamerus limestone, as¬ 
sociated with Pentamerus pseudogaleatus, etc. The finer surface markings do not dif¬ 
fer very essentially from S. cyclopterus , but the angular character of the sinus and 
mesial fold with obscure plications, the much more elevated beak of the ventral 
valve, and more numerous plications are distinguishing features. 
PLATE XXV. 
Fig. 2 a - c. Views of a single large specimen from the shaly limestone. 
Fig. 2 f. Enlargement of the surface. 
Fig. 2 g, h, i. Dorsal and front views of specimens from the Upper Pentamerus limestone. 
PLATE XXVIII. 
Fig. 7 a, b. Dorsal and ventral views of a larger specimen from the Upper Pentamerus 
limestone. 
Geological position and locality. In the shaly limestone of the Lower Helderberg 
group; Helderberg mountains and LIudson, rarely : Upper Pentamerus limestone; 
Schoharie and Helderberg mountains. 
