26 NAVICULEE. 
This species is very variable in size and outline. 
Hab. Marine. By far the most abundant of the littoral 
Navicule ; it is generally found in suitable localities, on 
the sandy beach, during the summer months, so that a 
sand-gathering can scarcely be made without obtaining it. 
The specimens sent to me from the sands at Dives in Nor- 
mandy by M. De Brébisson are exactly similar to those 
found on the Northumbrian shore ; so also are those of N. 
Barclayana of Prof. Gregory, sent by him to me from the 
estuary of the Clyde. 
Navicula angulosa, Gregory. 
Navicula angulosa, Greg. Trans. Micr. Soe. n. s. vol. iv. p. 42, pl. v. 
fig. 8; Ralfs, in Prit. Inf. p. 905; Rabenh. Europ. Diat. 
p. 176. 
Plate IV. fig. 4. 
V. elliptical-lanceolate, extremities subacute; striz oblique, 
marginal, elongated towards the extremities, shortened 
and angular in the middle, stout, costate, about 20 
in -001”; median blank space lanceolate with in- 
curved sides. 
Hab. Marine: littoral. Glenshira sand, estuary of the 
Clyde (Prof. Gregory) ; coast of Northumberland, abun- 
dant in localities where there is a slight admixture of fresh 
water (A. 8. D.). 
Navicula semiplena, Greville. 
Pinnularia semiplena, Grev.Quart. Micr. Journ. vol.vii. p. 84, pl.vi. fig.12. 
Navicula angulosa, var. B, Greg. Trans. Micr. Soc. n. s, vol. iv. p. 42, 
pl. v. fig. 8*. 
Plate IV. fig. 5. 
V. linear-elliptical, or elliptical-lanceolate, extremities sub- 
