O’Mrara—Report on the Irish Diatomacee. 345 
towards the ends; intermediate free space narrow, except in the cen- 
tre, where it is somewhat rhombically expanded. (Pl. 30, fig. 11.) 
Ralfs, in Pritch., p. 906. Donkin, N. H. Brit. Diat., p. 55, Pl. 
vill., fig. 8.—Pinnularia longa, Gregory, 8 SS Se a: Vol. lv., 1856, 
p- 47, Pl. 5, fig. 18. Rab. FI. ‘Bur. Alg., sect. 1., p. 218. 
Arran Islands; Stomachs of Ascidians, Roundstone Bay, Co. 
Galway. 
Navicula divergens, (Wm. Sm.) Fresh water. 
Valve oblong; length from about -0035 to :0055, breadth, from 
about :0007 to ‘0012. Gibbous in the middle, attenuated towards the 
slightly constricted and rounded extremities. Coste strong, con- 
vergent in the middle, and radiate towards the ends. Intermediate 
‘free space narrowed towards the ends, where there is a slight expan- 
sion; greatly expanded in the middle, reaching the margin in a tole- 
rably broad stauroform band. 
Ralfs, in Pritch., p. 896. Grunow, Verhand. der K. K. Zool. Bot. 
Gesel.. Band x., 1860, p. 523. Cleve, Om Svenska och Norska 
Diat., p. 225.—Pinnularia divergens, Wm. Sm., B. D., Vol.i., p. 57; 
Pl. xviii., fig. 177. Rab. Fl. Eur. Alg. sect. 1., p. 221. 
Drumoughty Lough, near Kenmare, County Kerry. Featherbed 
Mountain, Killakee, County Dublin. Bantry, County Cork. Lake 
near Castlewellan, County Down. Lough Mourne deposit, County 
Antrim. 
Navicula divergens, var. longa, (O’Meara.) Fresh water. 
Valve oblong, linear. Length about ‘0059; breadth about -0008; 
very slightly expanded in the middle and at the rounded ends. Coste 
as in the typical form; intermediate free space as in typical form, but 
scarcely reaching the margin, compared with which it is relatively 
narrower in middle, and broader at the ends. (Pl. 30, fig. 13.) 
Pond near the City of Armagh. 
Navicula divergens, var. elliptica, (O’Meara.) Fresh water. 
Like the typical species but broadly elliptical. 
Lough Mourne deposit, Co. Antrim. 
Navicula borealis, (Ehr.) Fresh water. 
Valve narrow, elliptical, with rounded ends. Length about :0015; 
breadth about :0004. Coste short, parallel; intermediate free space 
relatively wide, elliptical. (Pl. 30, fig. 14.) 
Kiitz. Bac. p. 96. T. xxviil., figs. 68 72, (where it is identified with 
Pinnularia borealis, Ehr.) Grunow, Verhand. der K. K. Zool. Bot. 
Gesel., Band x., 1860, p. 518.—Pinnularia borealis, Rab. Siissw. 
