358 Proceedings of the Royal Irish Academy. 



Dodder, Co. Dublin. Lougli Gill, Co. Keny. Powerscourt, Co. 



"WiekloTT. Lough, lloume deposit. 



Navicula fuha. (Donkin). Fresli water. 



Valve very mucli as the preceding, but smaller , and having th.e 

 stri® somewhat radiate; lenglb -0032, breadth -0007. (PI. 31, 



fig-2.) . 



There is great difficulty in identifying this form with that named 

 !N'avicula fulva by Ehrenberg, which several authors identify with 

 iNavicuIa cuspidata. 



This latter Smith has so accurately described, that there is no diffi- 

 culty in identifying it, and therefore, ujider the circumstances, I 

 attribute it to him. Donkin, too, has so figured IS'avicula fulva as 

 to render it equally distinctive, and for this reason I assign the 

 species to him. 



Donkin, 2s\ H., Brit. Diat,, p. 41, PL vi., fig. 9. 



Lough Gill, Co. Kerry. Dysart, Co. "^aterford. 



Nmicvla cuspis, IS". S. ^Marine. 



Yalves narrow, lanceolate ; length about -0044, breadth about '0008 ; 

 longitudinal sulci close to median line. Strise linear, slightly radiate ; 

 €nds cuspidate ; diy valve a light straw colour. (PI. 31, fig. 3.) 



From stomachs of Ascidians, Co. Clare. 



Navicida rliomhica. (Gregory). ITaiinc. 



Prustules on fi'ont view subquadrate ; slightly constricted angles, 

 rounded. On side view, valve elliptical. Stria3 fine, linear, converging 

 in the middle, radiate ; much finer and closer towards the ends ; length 

 •0026, breadth -0008. (PI. 31, fig. 4.) 



Gregoiy, Q. J. M. S., 1856, p. 38, PI. v., fig. 1. Ealfs, in Pritch, 

 p. 903. Pab. Fl. Eur. Alg., sect, i., p. 181. 



Barrow, Co. VTexford. Malaliide, Co. Dublin. Lough Gill, Co. 

 Kerry. Seashore near town of Galway. Breaches, Co. VTicklow. 

 Stomachs of Ascidians, Belfast Lough, Co. Antrim. Stomachs of Asci- 

 dians, Co. Clare. 



JSfavicula cmrulea, IN". S. Fresh water. 



Yalve narrow, lanceolate : ends much produced. Length -0022, 

 breadth -0005 ; longitudinal sulci close to median line. Striae linear, 

 convergent in middle, slightly radiate towards the ends ; dry valve of 

 ^ pale colour. (PL 31, fig. 5.) 



Lough ITask, near Tourmakcady, Co. llayo. 



