O’Mrara—Report on the Irish Diatomacee. 353 
Navicula bicapitata, var. cruetfera. Fresh water. 
Valve linear in the middle, attenuated towards the capitate ends. 
Length :0024; breadth :0006. Coste fine, radiate ; intermediate free 
space narrow, except in the middle, where it expands into a narrow 
stauroform band, reaching to the margin, and wider there than at the 
centre. (Pl. 30, fig. 33.) 
Pinnularia interrupta, Wm. Sm., B. D., Vol.i., p. 59, Pl. xix., 
fig. 184. Were it not for the figure of Smith, just referred to, it 
would be difficult to identify this form. Smith alleges that it is iden- 
tical with Stauroneis parva, Kiitz. Bac., p. 106, T. xxix., fig. 23; but 
that form, as described by Kiitzing, is elliptical, and has not capitate 
ends, in consequence of which I consider the species quite distinct. 
The specific name adopted by Smith was previously appropriated by 
Kiitzing for a form belonging to the genus Navicula, which that 
form still retains; for which reason I have changed the specific desig- 
nation.—Navicula parva, Ralfs, in Pritch., p. 897. This description is 
given obviously on the supposition that Pinnularia interrupta, (Wm. 
Sm.,) was identical with Stauroneis parva, Kitz. But a comparison 
of the figures renders the accuracy of this supposition more than 
doubtful. 
Pool near Glengarriff, Co. Cork. Lough Gill, Co. Kerry. River 
at Port-na-Crush, Co. Donegal. Ditch, Cushendun, Co. Antrim. 
Gavagh, Co. Derry. Pool near Glenchree, Co. Wicklow. 
Navicula bicapitata, var. constricta, (Grunow). Fresh water. 
Valves slightly incurved in the middle; ends much produced, nar- 
rowed, and but slightly capitate. Length -0025, breadth in middle 
"0006. Coste fine, radiate. Intermediate free space narrow, except 
in the middle, where it expands to the margin in a narrow stauroform 
band, widening at margin. (Pl. 30, fig. 34.) 
Navicula mesolepta, var. constricta, Grunow, Verhand. der K. K. 
Zool. Bot. Gesell., Band x., 1860, p. 521, T. iv., fig. 22, C. Inas- 
much as the typical form of Navicula mesolepta has persistent coste, 
whereas in the present case the coste are obviously interrupted in the 
middle, I prefer to regard this form as a variety of Navicula bicapitata. 
Featherbed Bog, Co. Dublin. Camolin, Co. Wexford. 
Nawicula termes, (Ehr.) Fresh water. 
Valve narrow, oblong. Length -0035, breadth :0006; slightly 
incurved in the middle; ends much produced, slightly constricted. 
Coste short, slightly radiate ; intermediate free space wide, sometimes 
reaching the margin in a stauroformband. (PI. 30, fig. 35.) 
Navicula termes, var. nodulosa, Kiitz. Bac., p.101, T. xxviii., fig. 71, 
in which the coste are represented as reaching the median line, 
whereas in the present form they are marginal. Kiitzing regards the 
