418 Proceedings of the Royal Irish Academy. 
Navicula minor, (Gregory). Marine or brackish water. 
Valve small; linear with cuneate ends, strie linear, nearly 
parallel in the middle; slightly radiate towards the ends; length 
"0012, breadth :0004. (Plate 34, fig. 35.) 
Gregory, Diat. of Clyde, p. 477, Pl. ix., fig. 1. Gregory mentions 
that in this species the strie do not reach the median line. In this parti- 
cular, the present form does not answer Gregory’s description, 
inasmuch as the striz plainly reach the median line, but in all other 
respects there is such agreement as to make me think the forms are 
identical. Ralfs agrees with Gregory in all particulars, p. 909. 
Donkin describes a form under this name which he regards as iden- 
tical with that described by Gregory. See N. H. Brit. Diat., p. 57, 
Pl. vii., fig. 7. The forms, however, are obviously different, that of 
Donkin being elliptical, lanceolate, while Gregory’s is linear, with 
cuneated apices. 
Piles of wooden bridge, Dollymount Strand, Co. Dublin. Lough 
Gill, Co. Kerry. 
(m) Diaphane. Stri@ not observable. 
Navicula perpusilla, (Grunow). Fresh water. 
Valve minute, linear, oblong, with rounded ends, and slightly 
expanded in the middle; length -0005, breadth -0002. (Plate 34, 
fig. 36.) 
Grunow, Verhand. der K. K. Zool. Bot. Gesell., Band x., 1860, 
pi dod, Ly, iv., fo 7 a. 
Lough Mask, near Tourmakeady, Co. Mayo. 
Navicula seminulum, (Grunow). Fresh water. 
Valve very minute, oblong, elliptical, with rounded ends; length 
‘0006, breadth -00025. (Plate 34, fig 37.) 
Grunow, Verhand. der K. K. Zool. Bot. Gesell., Band x., 1860, 
Pp. oo2, 1. iVv., fe 2. 
Lough Mask, near Tourmakeady, Co. Mayo. 
