2l6 N.WICULA. 



N. fusoides Grun. (Arc. Diat., p. 46, without figure). 



Valve narrow, linear-lanceolate, with apices more or less obtuse. Axial 

 area narrow. Striae, 21 to 25 in 1 c.d.m., gently radiant, crossed by two true 

 longitudinal lines. Length. 5 to 12 c.d.m. Breadth, 7 to 12 mill. d.m. 



Marine. Bahusie (Grun.). 



XIV. Sculpteae. 



Valve with apices rostrate, no median depression forming a pseudo-stauros N. sculpta. 



Valve with apices rostrate-capitate, with median depression simulating a 



pseudo-stauros . . . . . . N. sphseropliora. 



\ 



N. sculpta Ehr. (Mikr., pi. x. i, f. 5; h.v.h. Atl., pi. 12, f. 1*; 



Type No. 123), plate 4, fig. 194. 



Valve elliptic, with tapering apices, then longly rostrate, rostrum obtuse. 

 Raphe surrounded by a considerable hyaline zone. Striae feebly radiate, 15 to 

 16 in 1 c.d.m., formed of coarse puncta, interrupted near the raphe by a broad 

 depression of the valve in such a manner as to leave against it only a single 

 row of granules. The depression also continues but not so deep near one 

 of the margins of the valve in the form of a unilateral, indistinct, pseudo- 

 stauros. Length, 7 to 8 c.d.m. Breadth, 2-5 c.d.m. 



Fresh and brackish water. Rare. Parck near Louvain (P.G.), Blankenberghe. England, 

 Ireland, France, Norway. 



N. sphaerophora Kutz. (Bac, p. 95, pi. 4, f. 17; H.V.H. Atl., 

 pi. 12, f. 2 and 3* : Type No. 124), plate 4, fig. 195. 



Valve elliptic-lanceolate, with apices rostrate-capitate. Raphe surrounded 

 by a considerable hyaline area. Striae, 16 in 1 c.d.m., gently radiate, granular, 

 interrupted by narrow longitudinal depressions and by a broad transverse 

 depression, forming a very conspicuous pseudo-stauros. Length, 5^5 to 8 

 c.d.m. Breadth, 175 to 2 c.d.m. 



Fresh water. Not very common. Antwerp. Brussels (Delogne). Found throughout Europe. 



Probably only a variety of the preceding. 



XV. Serianteae. 



f Valve lanceolate, sometimes subrhomboidal, with subacute apices . . N. serians. 



< Valve lanceolate, narrow, with apices rostrate-capitate . . . N. exilis. 



I Valve cruciform .... . N. follis. 



