NAVICULA. 2 I 



b. VALVE WITH FINE PUNCTA. 



N. Scutum Schumann. ? (Preuss. D., p. 188, f. 45 ; H.v.H. 

 Atl., pi. ii, f. 14*), P^te 4, fig. 185. 



Valve narrowly elliptic, with apices not attenuate. Raphe surrounded 

 by a hyaline zone rather broad, irregular, enlarged round the central nodule. 

 Terminal nodules robust. Striae feebly radiate, finely granular, 16 in 1 c.d.m. 

 Length, 3 c.d.m. Breadth, 1 c.d.m. 



Freshwater. Very rare? Manage (P. G.), Prussia, Spitzbergen. 



aa. Apices produced rostrate. 



N. pusilla W. Sm. ! (s.b.d. i., P . 52, pi. 17, f. 145; h.v.h. 



Atl., pi. 11, f. 17*; Type No. 119), plate 4, fig. 186. 



Valve varying from broadly oval to elliptic-lanceolate, with apices produced 

 rostrate, rostrum truncate. Raphe surrounded by a small hyaline zone enlarged 

 round the central nodule ; striae distinctly granular, the median often of 

 unequal length, distant, about 10 in 1 c.d.m., the following ones more 

 compact, less robust,, about 14 in 1 c.d.m., radiate. Length, 3-5 to 4*5 c.d.m. 

 Breadth, about 2 c.d.m. 



Brackish water. Antwerp, England, Ireland, Denmark. 



II. Valve having two lunate sulci near the central nodule. 

 N. Schumanniana Grun. (N. Trochus (Ehr) ? n Schumann 



Preus. D., p. iS 9; pi. 2, f. 52 ; H.V.H. Atl., pi. 11, f. 21* = Coloneis CI ), 

 plate 4, fig. 187. 



Valve narrowly elliptic, with median portion strongly inflated ; raphe 

 surrounded by a feeble hyaline zone, conspicuously enlarged round the 

 central nodule, and showing there, on each side of the nodule, in the 

 longitudinal direction, a deep lunate sulcus; striae radiate, about 16 or 17 in 

 1 c.d.m. Length, about 3 c.d.m. Breadth at the median inflation, 1 c.d.m. 



Freshwater. Rare. Antwerp (P. G.), Brussels (Delogne). 



XII. Johnsonieae. 



N. JohnSOnii (W. Sm.)! (Pinnularia Johnsonii IV. Sm., S.B.D., 

 i., p. 58, pi. 19, f. 179; H.V.H. Atl. Supp., f. 28*), plate 4, fig. 188. 



