NAVICULA. 225 



N. levissima (Kutz. ?) Grun. (H.V.H. Atl., P i. 13, f. 13*), 

 plate 27, fig. 775. 



Valve linear, with rounded apices, at the median porrion often somewhat 

 inflated, stride slightly radiate-convergent, not reaching to the raphe, 13 in 

 1 c.d.m. at the median portion of the valve, 20 in 1 c.d.m. near the apices. 

 Length, about 3 c.d.m. Breadth, 75 c.d.m. 



Fresh and brackish water. Ard. Lieg. (De Wild.) England, France. 



N. Hebes Ralfs. (in Pritch. Inf., p. 896; N. obtusi IV. Sm., S.B.D., 

 i., p. 50, pi. 16, f. 140*; H.V.H. Type No. 75), plate 27, fig. 776. 



Valve oblong elliptic, contracted towards the apices which are inflated, 

 rounded, sometimes subtruncate. Striae 12 to T4 - 5 in 1 c.d.m., snbmarg.nal, 

 punctate, leaving round the raphe a considerable hyaline area, which is further 

 dilated round the central and terminal nodules. Length, about 6 c.d.m. 

 Breadth, 2 c.d.m. 



Fresh water. Ireland (W. Sm. ; O'M.). Scotland (Donkin ; W. Sm.). 



N. Pupula KlltZ. ! (Bac, p. 93, pi. 30, f. 40; H.V.H. Atl., pi. 

 13, f. 15-16*), plate 5, fig. 226. 



Valve linear, inflated at the median portion and at the apices, which are 

 rounded. Raphe surrounded by a narrow hyaline zone, abruptly enlarged 

 into a pseudo-stauros round the central nodule. Terminal nodules prolonged 

 laterally. Striae radiate, fine, 21 to 24 in 1 c.d.m. Length, r6 to 3-6 c.d.m. 

 Breadth, *5 to i'o c.d.m. 



Fresh water. Louvain (P.G.), Antwerp. France. 



