360 
PALAEONTOLOGY OF NEW YORK. 
marked by very fine, radiating, granulose striae which may be more or less 
interrupted by the concentric undulations. 
Ligamental area deep and strong. Anterior muscular impression sub-cir¬ 
cular, placed just within the anterior margin. Posterior scar large and shal¬ 
low, situated about one-third the length of the shell from the posterior 
extremity. Pallial line simple. 
Four characteristic specimens measure respectively 52, 53, 57 and 75 mm. 
in length, and 38, 35, 34 and 50 mm. in height. A specimen preserving its 
normal form and proportions has a length of 70 mm., height 45 mm., and a 
depth to both valves of 37 mm. 
In well-preserved specimens, this species is distinguished by the strong cinc¬ 
ture with parallel furrows extending to the base. It differs from G. elliptica in 
its more elongate form, less elevated and incurved beaks, less prominent umbo 
and greater development of the concentric undulations. 
Formation arid localities. In the arenaceous shales of the Hamilton group, in 
Schoharie, Otsego, Madison and Onondaga counties, and rarely in the softer 
beds of the group in Ontario and other counties in the western part of the State. 
Grammysia nodocostata. 
PLATE LV, FIGS. 1-11; PLATE LVI, FIGS. (2, 3?); AND PLATE LVII, FIGS. 7, 8. 
Gh’ammysia nodocostata, Halt., Prelim. Notice Lamellibranehiata, 2, p 50. 1870. 
“ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 55, figs. 1-11. 1883. 
Shell varying from medium size to very large; obliquely sub-ovoid; length 
about one-tliird greater than the height; basal margin broadly curving, 
flattened or constricted near the middle; posterior margin abruptly rounded 
below, and obliquely truncate above. Cardinal line straight, bordered by a 
well-defined escutcheon. Anterior end abruptly rounded below the lunule. 
Valves regularly convex below and in the posterior portion, becoming 
gibbous or ventricose above and in the umbonal region. Often extremely 
gibbous from vertical compression. 
Beaks sub-anterior, prominent and strongly incurved. Owing to pressure 
they often project beyond the anterior end. Umbo, in its upper portion, 
