416 Proceedings of the Royal Irish Academy, 



Nmicula linodis, (Ehr). Fresh, water. 



Valve small, narrow, incurved ; ends produced, apiculate. Striae fine, 

 linear, radiate; length -0012, breadth -0004; breadth in the middle 

 •00035. (Plate 34, fig. 29.) 



Kiitzing (Bac, p. 100, T. iii., fig. 35,) considers the form iden- 

 tical with that so named by Ehrenberg. Wm. Sm., B.D., Yol. i., 

 p. 53, PI. xvii., fig. 159. Eab. Stissw. Diat., p. 41, T. v., fig. 5, and 

 El. Eur. Alg., sect, i., p. 203. Ealfs, in Pritch., p. 893. Castracane, 

 Catalogo di Diat. raccolte nella Val. Intrasca, p. 12, Heiberg, De 

 Danske Diat., p. 83. Cleve, Om Svenska och i^Torska Diat., p. 227. 

 Donkin, IST. H. Brit. Diat., p. 38, PI. vi., fig. 3. Schumann, Diat. der 

 Hohen Tatra, p. 77. 



Powerscourt, Co. Wicklow. Lough Gill, Co. Kerry. Donkin 

 considers this species as one which occurs frequently in England; it 

 is, however, one of very rare occurrence in Ireland. 



Navicula dicephala, (Ehr.) Eresh water. 



Valve small, narrow, linear, narrowing towards the produced 

 slightly capitate ends. Stride obvious, convergent in the middle, radiate 

 towards the ends; length -0014, breadth -00055. (Plate 34, fig. 30.) 



Kiitz. Bac, p. 96, T. xxviii., figs. 60 and 62; these figures incor- 

 rectly describe the striae as parallel. Kiitzing attributes the species 

 to Ehrenberg. Wm. Sm., B. D., Vol. i., p. 53, PL xvii., fig. 157. 

 Grunow, Verhand. der K.K. Zool. Bot. Gesell., Bandx,, p. 538, T. iv., 

 fig. 45. RaKs, in Pritch., p. 902. 



Lough Gill, Co. Kerry. Lough IsTeagh, near Lurgan, Co. Armagh. 

 Camolin, Co. Wexford. Friarstown, Lucan, Killakee, Eiver Dodder, 

 Co. Dublin. Cushendun, Co. Antrim. Powerscourt, Co. Wicklow. 

 Lough Mourne deposit. 



Navicula rhjncocephala, (Kiitz.) Eresh water. 



Valve narrow, elliptical ; ends considerably produced, not capitate. 

 Striae distinct, closely moniliform, radiate ; length -0025, breadth 

 •0006. (Plate 34, fig. 31.) 



Kiitz. Bac, p. 152, T. xxx., fig. 35. Wm. Sm., B.D., Vol. i., 

 p. 47, PI. xvi., fig. 132. Grunow, Verhand. der K. K. Zool. Bot. 

 Gesell., Bandx., 1860, p. 530, T. iv., fig. 32. Heiberg, De Danske 

 Diat., p. 82. Ralfs, in Pritch., p. 900, PI. vii., fig. 68. Cleve, Om 

 Svenska och Norska Diat., p. 227. Schumann, Diat. der Hohen Tatra, 

 p. 68. Eab. El. Eur. Alg., sect, i., p. 196. Donkin, N. H. Brit. 

 Diat., p. 38, PI. vi., fig. 4. 



Eiver Dodder, ditch, Dundrum, Co. Dublin. Caumlough, near 

 Tralee, Co. Kerry. Ulster Canal, near Poyntzpass, Co. Armagh. 

 Kilcool, Co. Wicklow. 



