LAMELLIBRANCHIA TA. 
297 
Test of moderate thickness, marked by regular, prominent, lamellose striae. 
Anterior muscular impression strong, sub-circular. Inter-pallial area pus- 
tulose in the cast. Hinge thickened, carrying a single cardinal fold. Liga¬ 
ment extending about half the length of the cardinal line, strong and prom¬ 
inent, frequently preserved in specimens retaining the valves in conjunction. 
The striated area, anterior to the cardinal pit (fig. 19, plate xliii), does not 
appear to be an organic feature of the hinge, but is probably due to the 
infolding and impression of the surface striae. The hinge does not preserve 
striae posterior to the beak, as shown in the figure. 
Three characteristic specimens measure respectively 87, 82 and 38 mm. in 
length, and 39, 36 and 18 mm. in height. The smallest individual observed 
has a length of 10.5 mm. and a height of about 5 mm. 
This species differs from G. rugosa in having the umbonal ridge more direct, 
more prominent and strongly angular ; the anterior end is shorter and narrower, 
the posterior extremity more distinctly truncate and the surface of the shell is 
less rugose. 
■ Formation and localities. In the shales of the Hamilton group, Fultonham 
and Bear’s gulf, Schoharie county, and throughout the eastern and central 
portions of the State. 
Goniophora rugosa. 
PLATE XLII, FIGS. 7,8 a; and PLATE XLIII, FIGS. 4-7. 
Cypricardites rugosa, Conrad. Geol. Surv. N. Y., Ann. Rep., p. 53. 1841. 
/Sa7iguinolites vugosus (Conrad), Hall. Prelim. Notice Lamellibranchiata, 2, p. 37. 1870. 
Goniophora rugosa, Conrad. S. A. Miller. Cat. Amer. Pal. Foss., p. 192. 1877. 
“ “ “ Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 43, figs. 4-7. 
1883. 
Shell of medium or large size, sub-rhomboidal; length less than twice the 
height; basal margin gently curved, flattened on approaching the anterior; 
posterior margin sub-truncate, gently curving from the post-basal extremity 
to the cardinal line. Anterior end declining rapidly from the beaks and 
abruptly rounded below. Cardinal line gently arcuate, slightly oblique, 
extending for about two-thirds the length of the shell. 
