56 NAVICULEA. 
Hab. Marine. Abundant in sand-gatherings, coast of 
Northumberland (A. S. D.). Isle of Arran and Estuary 
of the Clyde (Prof. Gregory). 
Navicula arenaria, Donkin. 
Navicula arenaria, Donk. Quart. Mier. Journ. n.s. vol. i. p. 10, pl. i. 
fig. 9; Rabenh. Europ. Diat. p. 177. 
Plate VIII. figs. 5a & 58. 
Frustule on M. V. oblong, slightly constricted in the 
middle, extremities truncate. V. narrow, lanceolate, 
slightly constricted near the acute extremities ; strie 
costate, conspicuous, connivent, reaching to the me- 
dian line. 
Hab. Marine. Abundant in sand-gatherings, coast of 
Northumberland (A. 8. D.). 
Navicula apiculata, De Brébisson. 
Navicula apiculata, Bréb, Diat. de Cherb. p. 16, fig. 5; Ralfs, in Prit. 
Inf. p. 903. 
Pinnularia rostellata, Greg. Diat. of the Clyde, p. 16, pl. i. fig. 20, 
Plate VIIL figs. 6a & 66. 
Frustule on M. V. broad, oblong, constricted in the middle, 
extremities truncate, angles bevelled. V. linear, con- 
stricted into tapering, acute apices; strize reaching to 
the median line, very oblique towards the extremities, 
transverse opposite the central nodule, costate, some- 
what distant, about 18 in -001". 
This species is closely allied to N. cancellata, though 
smaller ; its frustule on M. V. is easily recognized from 
that of the latter by the oblique striz curving towards the 
