NAVICULA LATISSIMA. 17 
Subsection II. Valve elliptical or oval, with produced, obtuse 
extremities ; stric not interrupted. 
Navicula granulata, De Brébisson. 
Navicula granulata, Bréb. MS. ; Donkin, Trans. Micr. Soc. vol. vi. p. 17, 
pl. iii. fig. 19; Ralfs, in Prit. Inf. p. 903; Rabenh. Europ. 
Diat. p. 201. 
Plate III. fig. 1. 
Frustule large. V. broad, elliptical or linear-elliptical, 
with produced, broad, rounded extremities (sometimes 
elongated and constricted in the middle); median line 
narrow; striz reaching to the median line, some- 
what shortened around the central nodule, conver- 
gent, coarse, and widely granular. Dry valve dullish 
blue. 
Distinguished from N. latissima and N. humerosa by its 
much coarser strie. 
Hab. Marine. This large and beautiful species is very 
common in the sandy ripples of the sea-shore in many 
localities; but it does not occur in a living state in the 
tidal estuaries of our rivers. 
Navicula latissima, Gregory. 
Navicula latissima, Greg. Trans. Micr. Soc. vol. iv. n. s. p. 40, pl. v. 
fig. 4; Ralfs, in Prit. Inf. p. 903, pl. vii. fig. 70; Rabenh. 
Europ. Diat. p. 201. 
Pinnularia divaricata, O'Meara, Quart. Micr. Journ. n. s, vol. vii. p. 116, 
pl. v. fig. 7. 
Plate IIL. fig. 2. 
Frustule large. V. broadly oval or elliptical; extremities 
slightly, not prominently, produced by a gentle 
constriction, broad and rounded ; striz distinctly gra- 
c 
