224 NAVICULA. 



N. Bacillum Ehr. (Mikr., pi. 15, A., f. 38; H.v.H. Atl, pi. 13, 



f. 8*; in Type No. 548), plate 5, fig. 222. 



Valve linear, with apices rounded, thickened, smooth. Raphe surrounded 

 by a very narrow hyaline area, slightly enlarged round the central nodule and 

 at the apices of the valve. Striae slightly radiate, finely granular, 14 in 1 

 c.d.m. at the median portion of the valve, and about 17 at the apices. 

 Length, 5-5 c.d.m. Breadth, 1-5 c.d.m. 



Fresh water. Here and there throughout Europe. 



forma minor. (H.V.H. Atl., pi. 13, f. 10*), plate 5, fig. 223. 



Smaller and narrower, dimensions amounting to not more than about 

 a moiety of the preceding. Striae finer, 16 in 1 c.d.m. at the middle, 20 

 at the apices of the valve. 



Fresh water. Brussels Botanical Gardens (Delogne). 



N. bacilliformis Grun. (in CI. and Gr. Arct. D., 1880, p. 44, 

 pi. 2, f. 51 ; H.V.H. Atl., pi. is, f. 11*), plate 27, fig. 774. 



Valve linear, with apices rounded. Raphe surrounded by a hyaline zone, 

 very narrow, enlarged into a stauros round the central nodule. Striae feebly 

 radiate, convergent towards the apex of the valve, 10 to 15 in 1 c.d.m. 

 Length, 3-5 to 4^5 c.d.m. Breadth, about 1 c.d.m. 



Fresh water? Ard. Lieg. (De Wild.). Hickling, Norfolk, England (Kitton) ; Dover, England 

 (Grun.). 



N. subhamulata Grun. ! (H.v.H. Atl., pi. 13, f. 14*) plate 

 5, fig. 225. 



Valve linear, somewhat inflated at the median portion, with rounded 

 apices. Raphe surrounded by a very slight hyaline zone, somewhat dilated 

 round the central nodule. Terminal nodules comma-shaped. Striae some- 

 what radiate, very feeble, about 26 in 1 c.d.m. Girdle face with undulated 

 margins. Length, 2 c.d.m. Breadth, somewhat more than -5 c.d.m. 



Fresh water. Brussels (Delogne). 



N. pseudo-Bacillum Grun. ! (H.V.H. Atl., pi. 13, f. 9*), plate 

 5, fig. 224. 



Differs from JV. Bacillum by its larger hyaline area, its terminal nodules 

 prolonged laterally like a comma on each side and its finer striae, 21 in 

 1 c.d.m. in the middle, and 24 at the apices of the valve. Length, 4^5 c.d.m. 

 Breadth, about 1-5 c.d.m. 



Freshwater. Louvain (P.G.). Ard. Lig. (DeWild.). 



