NITZSCHIA CLAUSII HANTZSCH
Valve linear, slightly sigmoid, tapering to the sub-capitate ends; keel puncta, 11 in 10 µ; striæ subtle. L. 40 µ.
Abundant in Ridley Creek, Delaware Co. (Palmer).
Pl. [32], Fig. 20.
Obtusæ
NITZSCHIA OBTUSA WM. SM.
Frustule sigmoid, rounded at the ends; keel somewhat excentric, inflexed in the middle, the two median puncta distant; keel puncta, 5-6 in 10 µ; striæ, 26 in 10 µ. L. to 300 µ.
Along the coast.
Pl. [39], Fig. 16.
NITZSCHIA OBTUSA VAR. FLEXELLA H. L. SMITH