362 Proceedings of the Royal Irish Academy. 
been identified, were it not that authentic specimens were seen by 
Wm. Smith, who considers it identical with his Navicula patula, 
Bb. D., “Vol. 1.,:p: 49, Pl. xvi., fig.139. Ralfs in Priteh.; 9, 90a." aap: 
Sussw. Diat., p. 38, T. vi., fig. 61. Ifin this case the figure be cor- 
rect, it can scarcely be identified with Navicula latiuscula, Kiitz. 
Grunow, Verhand. der K. K. Zool. Bot. Gesell., Band x., 1860, p. 534, 
T. ty., fig.38. Donkin, N. H., Brit.Diat., p. 27; Ph ww., fe. ie eae 
Fl. Eur. Alg., sect: 1., p..182. 
Lough Corrib, Co. Galway. Killurin, Co. Wexford. Newtown- 
limayady, Co. Derry. Breaches, Newcastle, Co. Wicklow. 
Navicula barkeriana, N.S. Marine. 
Valve linear, elliptical, gradually attenuated towards the produced 
ends; striz linear, fine, close, distinctly radiate; intermediate free 
space wide, greatly expanded in the middle; median terminating to- 
wards the central nodule in elongated expansions; length ‘0052, 
breadth -0014. 
This form might be easily confounded with Navicula latiuscula,. 
from which it differs in the following features: the intermediate free 
space is much wider, the ends are produced, and the strie are radiate, 
and somewhat coarser. (Plate 31, fig. 16.) 
On sea-weeds, Dalkey, Co. Dublin. Breaches near Newcastle, Co. 
Wicklow. In both these gatherings there was a considerable admix- 
ture of fresh water forms; the marine forms, however, greatly prepon- 
derated. 
Navicula grunovit, (O’Meara). Fresh or brackish water. 
Valve broadly elliptical, longitudinal, marginal sulci very distinct ; 
intermediate free space wide, lanceolate, greatly expanded in the mid- 
dle; median line slightly undulate; strie fine, slightly radiate ; 
length -0040, breadth :0016. (Plate 31, fig. 17.) 
Navicula elegans, Grunow, Verhand. der K. K. Zool. Bot. Gesell., 
Band x., 1860, p. 534, T. iv., fig. 37. This author confounds this 
form with Navicula elegans, Wm. Sm., of which he states he had 
never seen a specimen ; and suggests that in case it should prove to be 
different from the last-named species it should be designated Navicula 
lacustris. Cleve, in his Diatoms of the Arctic Sea, p. 17, perceiving 
that the form was obviously distinct from Navicula elegans, adopts. 
Grunow’s alternative designation, which, however, must be aban- 
doned, as the name had been applied by Gregory to designate a very 
different form. Grunow found this species in fresh water as well as 
in slightly brackish water, so that there is a difficulty in ascertaining 
the habitat. I cannot clear up this difficulty, inasmuch as the only 
gathering in which the form occurred to me contained both marine and 
fresh water forms. 
Bellarena, Co. Derry. 
