406 Proceedings of the Royal Irish Academy. 



in tlie middle, convergent towards the ends ; a strongly developed sub- 

 marginal, longitudinal sulcus appears conformable witb the outer 

 margin of the valve ; length "0055, breadth "0020 ; breadth at the con- 

 striction -0011. (Plate 33, fig. 36.) 



This very striking form was exhibited by me some years ago, at a 

 meeting of the Dublin !Microseopical Club, at the house of ITr. Henry 

 Yickers, with whose name it is associated. 



Arran Islands ; Stomachs of Ascidians, Eoundstone Bay, Co. Gal- 

 way. 



(1.) Perstriatce. Strice reacMng tlie median line. 

 \ Birectce. &tri(Z parallel. 



Naxicida directa, (Wm. Sm.) Marine. 



Yalve narrow, lanceolate ; median line distinct- striae finely cos- 

 tate; length -0025, breadth -0003. (Plate 34, fig. i.) 



Ealfs, in Pritch., p. 906. Cleve, Om Svenska och 1^'orska Diat., 

 p. 224. — Pinnularia directa, "Wm. Sm., B. D., Yol. i., p. 56, PL xviii., 

 fig. 172. Eab. PL Eur. Alg., sect, i., p. 217. 



Malahide, Co. Dublin. Stomachs of Ascidians, Co. Clare. 



Navicula lanceolata, (Kiitz.) Presh water. 



Yalve lanceolate; strise punctate; length -0016, breadth -0004. 

 r" Kiitz. Bac, p. 94, T.ssviii., fig. 38; T. xxx., fig. 48. IS'either 

 of these figures indicates the character of the stri^; it is therefore 

 impossible to identify Kiitzing's species with certainty. Wm. Sm., 

 B. D., Yol. i., p. 46, suppl. PL xxxi., fig. 272. Eab. Fl. Eur. Alg., 

 sect, i., J). 171. This author attributes the species to Wm. Smith, 

 who has described it so that it can be easily recognised, and regards it 

 ■as distinct fi^om that so named by Xiitzing. 



Eiver Bann, near Coleraine, Co. Derry. Eilcool, Co. Wicklow. 

 Adregoole, Co. Gralway. 



Navicula exilis, (Kiitz.) Presh water. 



Yalve small, narrow, elliptical ; ends produced and slightlv capi- 

 tate ; strife obscure; length -0013, breadth -0003. (Plate 34, fig. 2.) 



Kiitz. Bac, p. 95, T. iv., fig. 6. This figure does not represent 

 the strioe. Grunow, Yerhand. der K. K. Zool. Bot. GeselL, Band x., 

 1860, p. 553, T. iv., fig. 30. Eab. Fl. Eur. Alg., sect. L, p. 198. 



Lough Mask, near Tourmakeady, Co. Mayo. 



