MIOCENE MOLLUSCA AND CRUSTACEA. 79 
Genus DONAX Linneus. 
DONAX VARIABILIS. 
Plate x1v, figs. 19 and 20. 
Donax variabilis Say: Jour. Acad. Nat. Sci., 1st ser., vol. 2, p.305; Tuom. and Holmes, 
Plioc. Foss. S. Car., p. 96, Pl. xx, fig. 6; ? Conrad, Proc. Acad. Nat. Sci. 
Phil., 1862, p. 573; Heilprin, Proc. Acad. Nat. Sei. Phil., 1887, pp. 401 and 405. 
Say’s description of this species is given as follows: “ Shell triangular; 
anterior margin obliquely truncate, cordate, suture a little convex; posterior 
hinge margin nearly rectilinear, suture indented; base a little prominent, 
beyond a regular curve near the middle; valves longitudinally striated with 
numerous equal, parallel, regular, impressed lines, hardly visible to the 
unassisted eye, and obsolete on the posterior margin; basal edge within 
crenate.” 
The description given by Tuomey and Holmes is in nearly the same 
language as the above and similarly expressed, and was evidently written 
with Say’s description before them. The only specimen which I have seen 
from the Miocene of New Jersey is an imperfect water-worn right valve, 
but as far as the characters are preserved it accords perfectly well with the 
recent shells found on our coast. 
Formation and locality: The specimen comes from the well-boring of 
Mr. Woolmans, at Atlantic City, N. J., and is the property of the Academy 
of Natural Sciences, Philadelphia. 
Family AMPHIDESMIIDZ. 
Genus AMPHIDESMA Lamarck. 
AMPHIDESMA BURNSI, 0. Sp. 
Plate xIv, figs. 16-18. 
Shell small, compressed, and very thin in substance, transversely ellip- 
tical in outline with nearly central beaks, which are small but somewhat 
elevated or pointed; rardinal margins moderately sloping from the beaks 
both anteriorly and posteriorly, the anterior side scarcely excavated in front 
of the beaks; basal margin broadly curved and the extremities of the shell 
nearly equally rounded, the posterior end being just perceptibly wider than 
