380 Proceedings of the Royal Irish Academy. 
Nawvicula brebissonit, (Kiitz). Fresh water. 
Valve linear, elliptical; ends somewhat rounded; length -0016, 
breadth -0005; coste fine, radiate; intermediate free space narrow, 
except in the middle, where it expands, reaching the margin in a 
stauroform band widening towards the margin. (Plate 30, fig. 24.) 
Kitz. Bac.’ p.93, |. ii,, fig. 49. ‘Ralisy im Priteh., in. S97. 
Grunow, Verhand, der K. K. Zool. Bot. Gesell., Band x., 1860, p. 519. 
—Pinnularia stauroneiformis, Wm. Sm., B.D., Vol.i., p. 57, Pl. xix., 
fig. 178. Rab. Fl. Eur. Alg., sect. i., p. 222. 
Drumoughty Lough, near Kenmare, Bantry, Co. Cork. Derry- 
lane Lough, Co. Cavan. Rathdrum, Featherbed Mountain, Co. Wick- 
low. Kullakee, Co. Dublin. Lough Gill, Co. Kerry. 
Navicula brebissonit, var. angusta, (Grun.) Fresh water. 
Valve narrow, elliptical; ends attenuated, and slightly rounded; 
length :0016, breadth 00025; cost fine, radiate; intermediate free 
space narrow, except in the middle, where it expands, reaching the 
margin in a stauroform band narrower than in the typical species. 
(Plate 30, fig. 25.) 
Grunow, Verhand. der K. K. Zool. Bot. Gesell., Band x., 1860, 
Dood, bv, fe ks. 
Derrylane Lough, Co. Cavan. Camolin, Co. Wexford. 
Navicula vcostauron, (Ehr.) Fresh water. 
Valve linear, elliptical; length -0028, breadth -0006; coste fine, 
radiate; intermediate free space narrow, except in the middle, where 
it expands into a narrow stauroform parallel band reaching the margin. 
(Plate 30, fig. 27.) 
Stauroptera icostauron, Ehr., as Grunow suggests, Verhand. der 
K. K. Zool. Bot. Gesell., Band x., 1860, p. 519.—Stauroneis icostauron, 
Kiitz. Bac., p. 106, T. xxix., fig. 10.—Pinnularia viridis, var. B., Wm. 
my, 5.s; Nol. a. ;p: 0%, APE xaitt., 12. foo, 15. 
Perrylane Lough, Co. Cavan. Adrigoole, Co. Kerry. Featherbed 
Mountain, Co. Dublin. Lake near Castlewellan, Co. Down. 
Navicula stauroptera, (Grunow). Fresh water. 
Valve linear, elliptical, with rounded ends; length -0025, breadth 
°0007; costz coarse, convergent in the middle, radiate towards the 
ends; intermediate free space narrow, except in the middle, where it is. 
much expanded, appearing sometimes to reach the margin, but really 
not so. (Plate 30, fig. 28.) 
Grunow, Verhand. der K. K. Zool. Bot. Gesell., Band x., 1860, p. 
516. Stauroptera parva, Ehr., according to Kiitzing.—Stauroneis 
parva, Kiitz. Bac., p. 106, T. xxix., fig. 23. Gregory has described a 
form as Pinnularia parva, Q.J.M.S., 1854, p. 98, Pl. iv., fig. 11. To 
