418 Proceedings of the Royal Irish Academy. 



Navicula minor ^ (Gregory), llarine or brackish water. 



Valve small; linear with, cnneate ends, strise linear, nearly 

 parallel in the middle ; slightly radiate towards the ends ; length 

 •0012, breadth -0004. (Plate 34, fig. 35.) 



Grregory, Diat. of Clyde, p. 477, PL ix., fig. 1. Gregory mentions 

 that in this species the striae do not reach the median line. In this parti- 

 cular, the present form does not answer Gregory's description, 

 inasmnch as the striae plainly reach the median line, but in all other 

 respects there is snch agreement as to make me think the forms are 

 identical. Ealfs agrees with Gregoiy 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, 

 PI. riii., 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. Loiigh 

 Gill, Co. Kerry. 



(m) BiaphancB. Strics not ohservahk. 



Navicula perpusiUa, (Gmnow). Freshwater. 



Yalve minute, linear, oblong, with rounded ends, and slightly 

 expanded in the middle ; length -0005, breadth -0002. (Plate 34, 

 fig. 36.) 



Gnmow, Yerhand. der K. K. Zool. Eot. Gesell., Band x., 1860, 

 p. 552, T. iv., fig. la. 



Lough Mask, near Tourmakeady, Co. Mayo. 



Nmicula seminulum, (Grunow). Fresh water. 



Yalve very minute, oblong, elliptical, with rounded ends ; length 

 •0006, breadth -00025. (Plate 34, fig 37.) 



Grunow, Yerhand. der K. E. Zool. Bot. Gesell., Bands., 1860, 

 p. 552, T. iv., fig. 2. 



Lough Mask, near Tourmakeady, Co. Mayo. 



