300 
PALAEONTOLOGY OF NEW YORK. 
Beaks sub-anterior, small and closely appressed ; umbo prominent; umbo- 
nal ridge more or less strongly defined and distinctly angular, extending to 
the post-basal extremity. 
Test of moderate thickness, marked by regular concentric thread-like 
striae, which are abruptly recurved on the umbonal ridge; anterior muscu¬ 
lar impression deep and strong. The pallia! line extends parallel to the 
basal margin, and abruptly recurves over the umbonal ridge, terminating in 
a large shallow posterior muscular scar upon the cardinal slope. The hinge 
is furnished with a strong triangular fold beneath the beak of the left valve, 
and a corresponding depression in the right valve. 
Three specimens measure respectively 90, 61 and 49 mm. in length, and 
49, 39 and 28 mm. in height. 
This species closely resembles G. Hamiltonensis, but differs principally in its 
proportionally shorter form, more convex basal margin and more direct umbo¬ 
nal ridge. 
Formation and localities. In the Hamilton group, Fultonham and Bear’s 
gulf, Schoharie county; Kelloggsville, Cayuga county, and on the shore of 
Cayuga lake, N. Y. 
Goniophora Ida. 
PLATE XLII, FIG. 13; and PLATE LXV, FIG. 20. 
Sanguinulites Ida, Hall. Prelim. Notice Lamellibranchiata, 2, p. 43. 1870. 
“ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 65, fig. 20. 1S83. 
Shell of medium size, elongate sub-elliptical; length about two and one-half 
times the height; basal margin regularly curved; posterior margin very 
obliquely truncate. Cardinal line straight, less than half the length of the 
shell. Anterior end gently declining from the beak, narrow, and abruptly 
rounded at the extremity. 
Valves regularly convex; cardinal slope depressed, and abruptly concave 
just above the umbonal ridge. 
Beaks at about the anterior third, small, appressed, slightly projecting 
