Pavonia, N. J. (artesian well); Kirkwood Pond, N. J.
Pl. [21], Fig. 15.
Diploneis EHR. (1840)
(diplos, double)
Valve elliptical or panduriform; median line enclosed in strongly siliceous horns corresponding to the lyre-shaped areas of Navicula lyra but never punctate; central nodule, quadrate; valve costate, or striate, or both; between the horns and the outer part are thinner spaces or sulci, and, in some species, outside of the sulci are narrow spaces known as lunulæ.
Chromatophores, two, upon the girdle or the valves. Pyrenoids have been found in one species only, D. interrupta.
DIPLONEIS ELLIPTICA (KUETZ.) CL.
Valve elliptical; central nodule large; sulci narrow, curved, close to the horns; striæ punctate, in rows radiating more and more toward the ends. Variable in size and in the coarseness of puncta which are from 10 to 13 in 10 µ (Cleve).
Cleve describes D. ovalis Hilse as having the central nodule rounded, but otherwise about the same as D. elliptica, and as equivalent to Navicula ovalis A. Schmidt (Atlas, Pl. 7, Figs. 33 to 36).
Very common in fresh water and occasional in brackish.