Chromatophores two, very short.
AMPHIPLEURA PELLUCIDA KUETZ.
Frustules free or in mucous masses. Valve fusiform; forks about one-fourth the length of the valve; striæ transverse, punctate, 36-40 in 10 µ (J. J. Woodward).
Occasional in the Delaware River.
Pl. [17], Fig. 9.
AMPHIPLEURA RUTILANS (TRENTEPOHL) CL.
Frustules enclosed in gelatinous tubes. Valve linear-lanceolate, obtuse at the ends; forks about one-third the length of the valve; striæ, 28 in 10 µ.
Conferva rutilans Trentepohl.
Schizonema dillwynii Wm. Sm.
Abundant at Belmar, N. J.