NAVICULA. 229 



N. exilissima Grun. ! (H.v.H. Atl., pi. 14, f. 30*; in Type 

 No. 141), plate 5, fig. 234. 



Valve linear-subelliptic ; striae fine, radiate, about 40 1 c.d.m., the 

 median ones somewhat more distant, details indistinct even with homogeneous 

 objectives, and in Prof. H. L. Smith's yellow medium. Length, from "5 to 

 i*o c.d.m. 



Fresh water. Groenendael (Delogne) ; Ard. Li^g. (DeWild.). 



N. binodis (Ehr., 1840) W. Sm. (S.B.D., i., p. 53, pi. 17, f. 159 ; 

 H.V.H. Atl. Supp., f. t, 3 * ; in Type No. 71), plate 5, fig. 235. 



Valve oblong, strongly constricted at the median portion, apices rostrate 

 capitate ; striae reaching almost to the raphe, feebly radiate, very delicate, 

 about 30 in 1 c.d.m. Length, about 2*5 c.d.m. Breadth at the constriction, 

 5 c.d.m. 



Fresh water. Manage (P.G.), Rouge-Clo!tre (Del.), Antwerp. Great Britain. 



N. lepidula Grun.! (H.v.H. Atl., pi. 14, f. 42*; Cahneis 



lepidula C/.), plate 5, fig. 236. 



Valve narrowly linear, apices rounded. Central nodule surrounded by a 

 considerable hyaline area. Striae reaching almost to the raphe, parallel, fine, 

 27 to 30 in r c.d.m. Length, about 2 c.d.m. Breadth, - 6 c.d.m. 



Fresh water. Groenendael (Delogne). 



N. perpUSilla Grun. (Ueber neue, etc., i860, p. 552, pi. 2, f. 7 ; 

 H.V.H. Atl., pi. 14, f. 22, 23*), plate 35, fig. 911. 



Valve minute, oblong, with rounded apices, inflated at the median portion. 

 Transverse striae very delicate, subparallel, indistinct. Length, 1-25 c.d.m. 

 Breadth, '5 c.d.m. 



Fresh water. Rouge Cloitre (Delogne), Scotland. Ireland (O'Meara). 



II. Frustules united in long bands (Diadesmis). 



* Valve with border furnished with coarse distant beads. 



N. Gallica (W. Sm.) H. Van Heurck. (H.V.H. Atl., pi. 



14, f. 39* ; Type No. 47), plate 5, fig. 237. 



Valve linear-elliptic or linear, with median portion somewhat inflated, 

 apices obtuse rounded, presenting throughout the length of the margin an 

 appearance of coarse beads. Raphe surrounded by a slight hyaline zone, 



