88 PALEONTOLOGY OF NEW JERSEY. 
CORBULA IDONEA. 
Plate xv, fig. 20. 
Corbula idonea Conrad: Am. Jour. Sci., Ist ser., vol. 23, p. 341; Miocene Foss., p. 6, 
Pl. x, fig. 6; Proc. Acad. Nat. Sci. Phila., 1862, p. 572; Meek, Cheek List, p. 
12; Heilprin, Proc. Acad. Nat. Sci. Phila., 1887, p. 403. 
“Shell triangular, ventricose, thick, with irregular impressed concentric 
lines on the inferior valve; superior valve with obsolete concentric undula- 
tions; the posterior submargin terminal, rectilinear, obtusely carinated, and 
marked posteriorly by a longitudinal furrow; inferior valve with the poste- 
rior extremity subrostrated, flexuous, the submargin obtusely carinated, and 
rough with transverse striz; tooth very thick and profoundly elevated.” 
(Conrad, Miocene Fossils, p. 6.) 
This is one of the largest of the American species of the genus, and is 
a very heavy and much thickened shell, and one not easily mistaken. The 
specimen recognized by Prof. A. Heilprin among the borings of the artesian 
well at Atlantic City, N.J., is a fragment of the larger thick valve and rep- 
resents less than one-third of the shell; still it is sufficient to identify the 
species and prove its occurrence in the Miocene within the State limits. The 
specimen is in the cabinet of the Academy of Natural Sciences at Phila- 
delphia. 
CORBULA SUBCONTRACTA, n. sp. 
Pl. xv, figs. 11-14. 
Shell small, the largest individual yet observed being rather less than 
one-fourth of an inch in length and about one-sixth of an inch in height; sub- 
ovate in outline, widest and shortest anteriorly, the beaks moderately large, 
and the valves very ventricose; posterior end pointed, the postero-cardinal 
slope narrow and very abrupt, and the umbonal ridge sharp. Surface of the 
valves marked by a few strong concentric ridges, which are round and 
abrupt, and are not continued on the postero-cardinal slope. Substance of 
the shell proportionally thick. In the interior the muscular imprints are 
well marked, while the cardinal tooth is only moderately developed, but has 
a very distinct ridge extending from its base parallel to the margin of the 
valve and a little below it, both on the anterior and posterior sides. 
