178 NAVICULA. 



var. Meniscus Schum. (H.V.H. Atl., pi. 8, f. 19*), plate 3, 

 fig. 102. 



Smaller, more broadly lanceolate, with apices diminishing more abruptly. 

 Length, 4 to 7 c.d.m. Striae, 7 or 8 in 1 c.d.m. 



Brackish water. Belgium, etc. 



var. Menisculus Schum. (H.V.H. Atl., pi. 8, f. 20, 21 and 22* ; 

 in Type No. 190), plate 3, fig. 103. 



Very small, lanceolate-elliptic, infinitesimally attenuate towards the 

 apices, or diminuate-rostrate. Hyaline space round the central nodule 

 sometimes next to nothing. Striae, 8 to 12 in c.d.m. Length, 2-5 to 3 

 c.d.m. 



Fresh water. Louvain (P.G.) 



id. forma Upsaliensis Grun. (H.V.H. All., pi. 8, f. 23, 24*), plate 

 3, rig- 104. 



More narrowly lanceolate, with apices more or less diminuate-rostrate. 

 Striae delicate from 8 to 12 in c.d.m. Length, 3 to 4 c.d.m. 



Fresh water. Louvain (P.G.) 



N. salinarun Grun. (Arct. Diat., p. 33, pi. 2, f. 34; H.v.H. Atl., 

 pi. 8, f. 9* Type No. 95), plate 3, fig. 108. 



Valve broadly lanceolate, sub-elliptic, with apices strongly rostrate, and 

 more or less capitate. Central nodule surrounded by a hyaline area very 

 elongated longitudinally. Striae rather strongly divided crosswise 14 to 16 in 

 1 c.d.m., the median radiant, the terminal feebly convergent. Lengih, 2*5 to 

 3-5 c.d.m. Breadth, 1 to i'5 c.d.m. 



Brackish water. Heyst (according to Deby) ; Antwerp (Scheldt, H.V.H.); Norfolk (England, 

 Kitton). 



N. cincta (Ehr !) Kutz. (Mik., pi. x. 2, f. 6; H.V.H. Atl., pi. 7, 

 f. 13-14*; Type No. 82), plate 3, fig. 105. 



Valve lanceolate, very narrow, with rounded obtuse apices ; central 

 nodule surrounded by a hyaline area somewhat extended transversely; striae 

 delicate, about 12 in 1 c.d.m., those round the central nodule much more 

 distant. Length, about 4 c.d.m. 



Fresh and brackish water. Aid. Lieg. (De Wild.). England. 



forma minuta. (H.V.H. Type No. 83); very small; Ostend. 



var. Heufleri Grun. (H.V.H. Atl., pi. 7, f. 12 and 15*), plate 3, 

 fig. 106. 



_ Smaller with median hyaline space round, striae more robust and more 

 distant, about 10 in 1 c.d.m. Length, about 2 to 2-5 c.d.m. 



Somewhat brackish water Austruweel near Antwerp (P.G. ). 



