LAMELLIBRANCHIA TA. 
359 
plications. In its general form it also somewhat resembles G. Canadensis of 
Billings, but is otherwise very distinct. 
Formation and locality. In the Corniferous limestone, Delaware, 0. 
Grammysia bisulcata. 
PLATE LXV, FIGS. 1-16; PLATE LVI, FIG. 1; and PLATE XCIII, FIG. 25. 
Pholadomya anomala, Goldfuss. Pet. Germ., p. 272, pi. 157, fig-. 9. 1S34-1840. 
Pterinea bisulcata, Conrad. Geol. Surv. N. Y., Ann. Rep., p. 116. 183S. 
Cypricardites bisulcata, Conrad. Geol. Surv. N. Y., Ann. Rep., p. 52. 1841. 
Grammysia Hamiltonensis, De Verneuil. Bull. Soc. Geol., France, 2d ser., vol. iv, p. 696. 1847. 
Cardinia Hamiltonensis, D’Orbigny. Prod. Paleon., vol. 1, p. 76. 1850. 
Grammysia bisulcata (Conrad), Hall. Prelim. Notice LamellibrancMata, 2, p. 49. 1870. 
“ “ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 54, figs. 1- 
16; pi. 56, fig. 1. 1883. 
Compare Nucula cingulata, Hisinger. Leth. Svecica, pi. 39, fig. 1; supplement, p. 6. 1837. 
Shell large, ovoid; length once and a half the height; basal margin broadly 
curved, with a constriction near the middle of its length; posterior margin 
abruptly rounded below and broadly curving or sub-truncate above. Cardi¬ 
nal line nearly straight, more than half as long as the shell. Anterior end 
abruptly rounded below the deep lunule. 
Yalves regularly convex below and gibbous or ventricose in the middle 
and above. 
Beaks sub-anterior, strong, incurved over the cardinal line. Umbo promi¬ 
nent, gibbous, with a cincture consisting of a strong fold with a furrow on 
each side, extending from the beak to the basal margin at about the middle 
of its length; this feature, alternating on the two sides, gives a sinuosity to 
the line of junction of the valves. 
Entire surface marked by line concentric striae, which, on some portions oi 
the shell, are aggregated into fascicles; and by strong, regular, persistent, 
concentric ridges or folds, which are stronger upon the anterior part of the 
shell and distinctly undulated in crossing the cincture. The undulations occa¬ 
sionally become obsolete in the lower and posterior part of the shell, and 
sometimes are to be seen only on the anterior and umbonal portion. In well- 
preserved specimens the surface, especially in the umbonal region, is also 
