Pl. [36], Fig. 6.
SURIRELLA ANGUSTA KUETZ.
Valve linear, with cuneate ends; otherwise as in S. pinnata.
Fresh water.
Pl. [36], Fig. 8.
S. pinnata, S. panduriformis, and S. angusta have a narrow central area, and differ from S. ovalis which has short costæ.
SURIRELLA OBLONGA EHR. ?
Valve elliptical-lanceolate, with obtuse ends; costæ, marginal, 2½ in 10 µ; median area granulate; pseudoraphe narrow, lanceolate, scarcely visible; striæ about 18 in 10 µ. L. 60 µ.
Blue clay. Rare.
Pl. [35], Fig. 9.