352 Proceedings of the Royal Irish Academy. 



and capitate ; costae strong, convergent in tlie middle, and radiate to- 

 wards the ends ; intermediate free space narrow, except in tlie middle, 

 where it is much expanded, reaching to the margin. (Plate 30,. 

 fig. 31.) 



Kiitz. Bac, p. 101, without a figure. This author identifies the- 

 species with Pinnularia isocephala, Ehr. Kitton, Science Gossip^ 

 June, 1868, p. 132. — Pinnularia monile. Rah. Fl. Eur. Alg., sect, i.^ 

 p. 220. 



Pond near the city of Armagh. Eriarstown, Co. Dublin. 



Navicxda nodosa, (Ehr.) Eresh water. 



Yalve long and narrow ; length '0024, breadth '0005 ; margin un- 

 dulate, with three nearly equal inflations ; costse short, not very close, 

 convergent in the middle, radiate towards the ends ; intermediate free- 

 space wide, expanded in the middle. (Plate 30, fig. 26.) 



Kiitz. Bac, p. 101. T. xxviii., fig. 82. This author regards the- 

 form as identical with jSTavicula nodosa, Ehr. Infus., 1838, p. 179, T. 

 xiii., fig. 9. Eab. Siissw. Diat., p. 41, T. vi., fig. 86. Gregory, 

 Q.. J. M. S., Yol. iv., 1856, p. 3, PI. i., fig. 5. Pinnularia nodosa,. 

 AYm. Sm., B.D., Yol. ii., p. 96. 



Eriarstown, Featherbed Mountain, Co. Dublin. Hiver Slaney^ 

 near Eallurin. Camolin, Co. Wexford. Lake near Castlewellan, Co. 

 Down. Kilcool, Lugnaquilla Mountain, Co. Wicklow. 



JSfavicula nodosa, var. staurophora, (Grunow). Eresh water. 



Yalve smaller than in the typical species; length '0016, breadth 

 •00025; inflations not so distinct ; intermediate free space expanding^ 

 in the middle into a distinct stauroform band reaching the margin. 

 (Plate 30, fig. 26 a.) 



]S"avicula nodosa, Grunow, Yerhand. der K. K. Zool. Bot. Gesell.^ 

 Band x., 1860, p. 521, T. ii., fig. 21. 



JSfavicula bicajntata, (O'Meara). Eresh water. 



Yalves small ; length '0020, breadth '0006 ; linear, attenuated 

 towards the capitate ends ; costae fine, convergent at the centre, radiate 

 towards the ends ; intermediate free space narrow, except at the 

 middle, where it is roundly expanded, not reaching the margin. 

 (Plate 30, fig. 32.) 



Pinnularia biceps, Gregory, Q.J. M.S., 1856, p. 8, PI. i., fig. 28. 

 Kiitzing has described a form under the name of JN'avicula biceps, Bac, 

 p. 96, T. xxviii., fig. 51, wliich is widely different from the present. 

 Gregory's specific name must therefore be dropped. 



Drumoughty Lough, near Kenmare, Co. Cork. Cawn Lough,, 

 near Tralee, Co. Kerry. Biver Bannow, near Clonegal, Co. Carlow. 

 Kilcool, Co. Wicklow. Camolin, Co. AYexford, 



