NAVICULA. 209 



var. angulosa. (A 7 , angulosa Greg., H.V.H. Atl., pi. 11, f. 10*; 

 in Type No. 116), plate 4, fig. 177. 



Hyaline area very small, angular. 



Marine. Scheldt at Antwerp ; Blankenberghe. England (Donkin), Scotland (Gregory), 

 Ireland (O'M.). 



var. minor Grun. (H.V.H. Atl., pi. 11, f. n*), plate 4, fig. 178. 



Much smaller than the type form, scarcely 2-5 c.d.m. in length, 10 or 

 1 1 striae in 1 c.d.m. 



Marine. Ostend. 



var. Barklayana Greg.? (N. Barklayana Greg.'! H.V.H. Atl., 

 pi. 11, f. 12*), plate 4, fig. 179. 



Valve with margins almost straight, abruptly attenuate. 



Marine. Blankenberghe. 



var. semiplena. (Pinnularia semiphna Grev.). 



Valve linear-elliptic, narrow, very elongate. Marginal striae vigorous, 

 10 in 1 c.d.m. Length, about 8 c.d.m. Breadth, about 2 c.d.m. 



Marine. Blankenberghe (H.V.H.). Coasts of Scotland (Gregory), and probably else 

 where. 



Observ. The striae of N. pulpebralis in my plates have erroneously been 

 drawn punctate, and so described in my Synopsis. In 1882 I fell into the 

 same error as my predecessors W. Smith, Grunow, etc. Recent study, with 

 the aid of better objectives, has proved to me that they are in reality 

 irresolvable costw. 



X. Abbreviate. 



Valve with considerable hyaline space, rounded, i Strias delicate > feebl y radiate N - brevis - 



abruptly diminuate . . ,].. , , , 



J \ Striae robust, strongly radiate . N. elegans 



N. brevis Greg. (Diat. of Clyde, p. 6, pi. 1, f. 4 ; H.V.H. Atl., 

 pi. 11, f. 19*), plate 4, fig. 180. 



Valve elliptic, with apices diminuate-rostrate, rostrum very broad. Raphe 

 surrounded by a rather broad hyaline zone, dilating round the central nodule 

 into a considerable hyaline space, rounded, abruptly diminuate. Striae radiate, 

 finely punctate, 14 in 1 c.d.m. 



Marine. Washing of mussels (Deby). Very rare form. England, Scotland (Greg. ), Finmark, 

 Bahusie. 



var. elliptica (H.V.H. Atl., pi. 11, f. 18*; = C. brevis var. 

 vexans CI.), plate 4, fig. 181. 



This form, with rounded apices, not diminuate-rostrate, is much 

 commoner than the type form. It is found in brackish water, but has 

 not yet been found in Belgium. 



p 



