NAVICULA MARINA. 19 
Navicula brevis, Gregory. 
Nawicula brevis, Greg. Diat. of the Clyde, p. 6, pl. i. fig. 4; Ralfs, in 
Prit, Inf. p. 899; Rabenh. Europ. Diat. p. 192. 
Plate III. fig. 4. 
Frustule small. V. short, broad, elliptical, slightly con- 
stricted into produced, broadly rounded extremities ; 
strie fine, about 85 in -00L", slightly inclined, not 
reaching to the median line, and much shortened 
around the central nodule. 
Hab. Marine. Lamlash Bay Isle of Arran (Prof. Gre- 
gory) ; Cumbrae (Prof. Walker Arnott). 
Navicula marina, Ralfs. 
Navicula marina, Ralfs, in Prit. Inf. p. 903; Rabenh. Europ. Diat. 
p. 202. 
Navicula punctulata, Smith, Synop. vol, i, p. 52, pl. xvi. fig. 151. 
Plate III. fig. 5. 
V. broadly oval, with very slightly produced, rounded ex- 
tremities ; striz reaching to the median line, oblique, 
convergent opposite the centre, about 32 in ‘001", 
distinctly granular. 
Hab. Brackish water. Poole Bay-and Seaford, Sussex 
(Prof. Smith). In brackish water near Hull, rare (Mr. 
Norman). Brackish water near Liverpool (Mr. Comber). 
Brackish water, estuary of R. Wansbeck, Northumberland, 
abundant (A. 8. D.). Although this species is described 
as marine in the ‘Synopsis’ of Prof. Sinith, I have never 
found it in purely marine localities, where its congener 
N. granulata is found. 
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