(named after Alphonse de Brébisson, the distinguished French naturalist)
Frustules stipitate; valve lanceolate; striæ transverse in the middle, radiate at the ends. Median area narrow, central nodule elongated, terminal fissures at a distance from the ends. Valve with an outer finely punctate stratum.
At one end of one valve in each frustule is found a conspicuous punctum, the plasma pore of Otto Mueller, through which the frustule is connected with the gelatinous stipe, analogous to the pore in Diatoma connecting the zig-zag frustules.
Chromatophore single, lying on one girdle and passing over to each valve.
BRÉBISSONIA BŒCKII (KUETZ.) GRUN.
Valve lanceolate, with sub-acute apices; striæ, 3-4 in 10 µ, not reaching the median line.
Blue clay. Very rare. Common in brackish water at Chestertown, Md. (T. C. Palmer)
Pl. [17], Fig. 7.
BRÉBISSONIA PALMERII, N. SP.
Valve rhombic-lanceolate, with cuneate ends and produced apices. Central nodule more elongate and terminal fissures further from the ends than in B. bœckii.