Psammamphora
AMPHORA ARENARIA DONK.
Frustule hyaline, rectangular, slightly tumid in the middle, with rounded angles. Valve linear with broad ventral side and straight or sinuate ventral margin. Striæ, 24-27 in 10 µ (Cleve).
Common along the coast.
Pl. [15], Fig. 17.
The distinction between A. obtusa and A. arenaria is not always evident if the valves alone are seen. The former has a complex zone, the latter a simple zone, and the valve has finer striæ. Cleve's descriptions and references in regard to these two forms do not agree with the descriptions and figures of H. L. Smith, or with the figures of Schmidt. The valves of most Amphoræ are capable of assuming various outlines according to their position.
AMPHORA OCELLATA VAR. CINGULATA CLEVE
Frustule rectangular. Valve linear, with dorsal margin arcuate and the ventral margin straight. Central nodule with a stauros on the dorsal side.
Squan River, N. J.
Pl. [15], Figs. 14 and 15.