O'Meara — Report on the Irish Diatomacece. 381 



latter, I presume, to be the present one. Ralfs, (in Pritch., p. 903), 

 says the only species TPith which this could be confounded is 

 jSTavicula firma, but it appears to me that it is more likely to be 

 confounded with jS'avicula punctata. Eab. Fl. Eur. Alg., sect, i., 

 p. 200. 



Lough llask, near Tourmakeady, Co. j\Iayo. Lough ]N'eagh, near 

 the town of Antrim. Lough Gill, Lower Lake, Killamey, Pedlass 

 Lake, near Dingle, Co. Kerry. 



NavicuJa macidosa, (Donkin). lEarine. 



Yalre linear, elliptical ; ends slightly produced and somewhat 

 cuneate ; intermediate free space linear, naiTOW, slightly expanded 

 around the central nodule ; striae distinctly moniliform, parallel in 

 the middle, and divergently radiate towards the ends; length '0027, 

 breadth -0008. (Plate 32, 'fig. 12.) 



Donkin, 2^. H. Brit. Diat., p. 25, PL v., fig. L 



Piles of wooden bridge, DoUymount Strand, Co. Dublin. 



Navicula sciiteUoides, ("Wm. Sm.) Presh water. 



Valve nearly orbicular, minute ; intermediate fi'ee space narrow, 

 linear, slightly expanded in the middle ; striae distant, moniliform, 

 divergently radiate ; length, -0009 ; breadth, -0008. (Plate 32, fig. 13.) 



Wm. Sm., B. D., Yol. ii., p. 91. Grunow, (Verhand. der K. K. 

 Zool. Bot. GeselL, Band x., 1860, p. 533, T. v., fig. 15), places it in 

 intimate connexion with Xavicula lyra and jSTavicula hennedyi, but the 

 position I assign to it seems to me more appropriate. Bafls, in Pritch., 

 p. 909. Eab. PL Eur. Alg., sect, i., p. 185. 



Lough Xeagh, near Antrim. Lough !Mask, near Toiu'makeady, 

 Co Mayo.- 



ITavicula 2>usiUa, (Wm. Sm.) Brackish water. 



Yalve small, broadly elliptical, ends produced ; narrow, rounded ; 

 intermediate free space narrow, linear, expanded in the middle ; stria3 

 distinctly moniliform ; convergent in the middle, and radiate towards 

 the ends ; more distant in the middle, closer towards the ends ; 

 length -0015 ; breadth, -0008. (Plate 32, fig. 14.) 



Wm. Sm., B. D., Yol. i., p. 52, PI. xvii., fig. 145. Ptalfs, in 

 Pritch., p. 900. Cleve, Om Svenska och Xorska Diat., p. 227. It is 

 likely that the form mentioned by Cleve may be a distinct species, as 

 he attributes it to fresh water. Eab. PL Eur. sect, i., p. 193. 

 Donkin, jST. H. Brit. Diat., p. 20, PI. iii., fig. 6. — [N'avicula tumida, 

 var. subsalsa, Grunow, Yerhand. der K. K. Zool. Bot. Gesell., Band 

 X., 1860, p. 537, T. iv., fig. 43. 



Brackiph ditch near town of Tv^exford ; Tacumshane, Co. A7exford. 

 Ballysodare, Co. Sligo. Breaches near ^^ewcastle, Co. Wicklow. 



2T2 



