Pl. [2], Fig. 10.
CYCLOTELLA COMTA (EHR.) KUETZ.
Valve with marginal striæ well marked, each third or fourth costa more robust than the others. Central part finely striated, the striæ punctate, radiating.
Fresh water.
Pl. [2], Fig. 7.
The form here figured is probably the variety radiosa Grun. and is from a New England specimen. It is quite likely to occur in this locality.
CYCLOTELLA OPERCULATA (AG.) KUETZ.
Frustules in zone view undulated. Angles rounded. Marginal costæ alternating with minute spines; centre nearly smooth, depressed, convex or flexuose.
Fresh water.
Pl. [2], Figs. 5 and 6.