50 NAVICULEE. 
into two oblong lobes with rounded or subcuneate 
obtuse extremities; striz distinctly granular, about 
20 in 001", transverse in the middle, oblique towards 
the extremities, outer band conspicuous, inner faint, 
linear; central nodule large, bulging. 
Hab, Salt water. Glenshira sand, Estuary of the Clyde 
(Prof. Gregory). Cresswell, Northumberland (A. S. D). 
Navicula Musca, Gregory. 
Navicula Musca, Greg. Diat. of the Clyde, p. 7, pl. i. fig. 6; Ralfs, in 
Prit. Inf. p. 893; Rabenh. Europ. Diat. p. 204. 
Navicula constricta, Grunow, in Wien. Verh. 1860, p. 585, t. i. fig. 18; 
Rabenh. Europ. Diat. p. 205. 
Plate VII. fig. 6. 
Frustule small. V. short, with a sinuous constriction in 
the middle and cuneate acute, or subacute, extremi- 
ties; outer section of striz coarse and obscurely 
granular, about 18 in 001", oblique, inner section 
obscure; median line broad. 
The indistinctness of the inner band of strie within the 
longitudinal intersecting groove gives to this species the 
appearance of having a marginal band of coarse costate- 
looking strie. 
Hab. Salt water. Estuary of the Clyde and Loch Fine 
(Prof. Gregory). 
Navicula Bombus, Ehrenberg. 
Navicula Bombus, Ehren., Kiitz. Spec. Alg. p. 83; Ralfs, in Prit. Inf. 
p. 893; Greg. Diat. of the Clyde, p. 12, pl.i. fig. 12; Rabenh. 
Europ. Diat. p. 204. 
Pinnularia Bombus, Ehren. Berlin. 1844, 
Diploneis Bombus, Ehren, Mikrogeo. t. xix. fig. 31, 
