4 
342 Proceedings of the Royal Irish Academy, 
among the Nobiles, to be only a variety of Navicula viridis. Speaking 
of this former, he says, ‘‘it appears to me to be only a variety of Nav. 
viridis, tolerably numerous figures (especially from specimens out of 
the Kieselguss of Franzensbad), which lie before me, present such 
manifold transitions, as well in respect to the appearance of the stria- 
tion as to the outline of the form, that m most cases it is difficult to 
decide whether the specimen should be referred to one or the other.’ 
Verhand. der K. K. Zool. Bot. Gesel., Band x., 1860, p.. 515. 
The correctness of this remark is obvious to all careful observers, 
but still the species seem to be distinct. The following characters 
seem to distinguish gNavicula viridis from N. major; the coste are 
finer and less radiate; the median free space is narrower and less ex- 
panded around the central nodule, and the normal outline is linear 
elliptical. 
Kitz: Bact; sp. 97,Dv iva tien 18; Rallis, ain Prigch; pO Ogre lines 
figs. 185, 186. Grunow, Verhand. der K. K. Zool. Bot. Gesel., Band 
x., 1860, p. 518. Heiberg, De Danske Diat., p. 80. Cleve, Om 
Svenska och Norska Diat., p. 223.—Pinnularia viridis, Wm. Sm., 
BOD. Vol. 4., p:-64, Pl xvi, fig 163)' Rabe Stssw- iat, p. aoe 
v1., fig. 4. 
' Featherbed Mountain, Friarstown, Co. Dublin. River Erne, near 
Crossdoney, Derrylane Lough, Co. Cavan. Ditch near Cushendun, 
Co. Antrim, Drumoughty Lough, near Kenmare, Lower Lake, Iul- 
larney. River near Glencar, Co. Kerry. Greenane Carrickmacreilly 
Hill, Lugnaquilla, Co. Wicklow. Lough Corrib, Co. Galway. Lough 
Mourne deposit, Sub-peat deposit, Dromore, Co. Down. 
Navicula alpina, (Wm. Sm.) Fresh water. 
Length of valves about ‘0060, breadth about -0018; broadly ellip- 
tical, with rounded ends; intermediate free space wide, but slightly 
expanded around the central nodule; costs broad, convergent in the 
middle, and radiate towards the ends. (Pl. 30, fig. 4. 
Grunow, Verhand. der K. K. Zool. Bot. Gesel., Band x., 1860, p. 
522.—Pinnularia alpina, Wm. Sm., B. D., Vol. 1., p. 55, Pl. xviii., fig. 
168. Rab. Fl. Eur. Alg., sect. 1, p. 213. 
On the slopes of Slieve Donard, Co. Down. Killakee, Featherbed 
Mountain, Co. Dublin. 
Navicula pachyptera, (Ehr.) Fresh water. 
Frustules regularly quadrangular on front view; length of valve 
about ‘0034, breadth about :0013; slightly inflated in the middle, 
rounded at the ends; intermediate free space but slightly expanded in 
the middle; costz broad, slightly converging in the middle, and nearly 
parallel for the remainder. (Plate 30, fig. 5.) 
Kiitz.. Bac:, p. 98, T. xxvua.. fig/68. Ralfs; im: Prifch:;' p2896, 
who considers the species distinct from Pinnularia lata, Wm. Smith, 
