406 Proceedings of the Royal Irish Academy. 
in the middle, convergent towards the ends; a strongly developed sub- 
marginal, longitudinal sulcus appears conformable with 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 Microscopical Club, at the house of Mr. Henry 
Vickers, with whose name it is associated. 
Arran Islands; Stomachs of Ascidians, Roundstone Bay, Co. Gal- 
way. 
(l.) Perstriate. Stri@ reaching the median line. 
| Directe. Strie parallel. 
Navicula directa, (Wm. Sm.) Marine. 
Valve narrow, lanceolate ; median line distinct; strie finely cos- 
tate; length -0025, breadth -0008. (Plate 34, fig. 4.) 
Ralfs, in Pritch., p.906. Cleve, Om Svenska och Norska Diat., 
p. 224.—Pinnularia directa, Wm. Sm., B. D., Vol. i., p.56, Pl. xviii., 
Het 2> Tab. “Mi Mur, Ales sect. 1: i. ori. 
Malahide, Co. Dublin. Stomachs of Ascidians, Co. Clare. 
Navicula lanceolata, (Kitz.) Fresh water. 
Valve lanceolate; striz punctate; length -0016, breadth -0004. 
Kutz, Bac., ». 94, (loascvui., fig. 36> xxx die a8. Wemlier 
of these figures indicates the character of the striz; it is therefore 
impossible to identify Kiitzing’s species with certainty. Wm. Sm., 
B.;,. Vol..1.,p. 46, suppl Pk xxa.,die, 2712, . Rab are ie 
sect. i., p. 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 from that so named by Kiitzing. 
River Bann, near Coleraine, Co. Derry. Kailcool, Co. Wicklow. 
Adregoole, Co. Galway. 
Nawvicula exilis, (Kiitz.) Fresh water. 
Valve small, narrow, elliptical; ends produced and slightly capi- 
tate ; strie obscure; length -0018, breadth :0003. (Plate 34, fig. 2.) 
Kjitz. Bac., p. 95, T. iv., fig. 6. This figure does not represent 
the strie. Grunow, Verhand. der K. K. Zool. Bot. Gesell., Band x., 
1860, p..553, T. 1v., fig. 30. . Rab. Fl. Eur. Alg:, sect. 1., p. 198. 
Lough Mask, near Tourmakeady, Co. Mayo. 
