O’Mrara—Report on the Irish Diatomacee. 303 
‘to be discriminated on the ground of habitat from Syn. pulchella. 
Speaking of this last named form, Grunow sagaciously remarks, 
‘‘ Whether this species is actually distinct from the preceding (Syn. 
fasciculata, Grun. = to Syn. gracilis, Wm. Sm.), admits of considerable 
doubt. Single frustules are not distinguishable. The separation is 
founded only on the union in larger fans upon a stipes often tolerably 
thick, which is by no means constant, and the occurrence in fresh 
water.” Verhand der K. K. Zool. Bot. Gesel., Band xu., 1862, 
p. 892. I am disposed to regard all these various forms as merely 
varieties cf Syn. pulchella—and for this reason, that I have noticed 
them more or less mixed together in gatherings from fresh water 
localities, as well as in places where the water was slightly brackish, 
and almost always exhibiting features of mutual relationship. 
Synedra pulchella, (Kiitz.) Fresh water. 
On front view linear, slightly attenuated towards the ends; on 
side view narrow, lanceolate, slightly capitate; the median ring 
strongly marked. (Pl. 28, fig. 17.) 
I have never seen the median ring so round or so decided in its 
character as appears in Smith’s figure of the specics. 
Mubze bac. D960. be xxix tie. S/t) Wm, osm, B.D. Vol. i, 
p. 70, Pl. x1., fig. 84, Supp., Pl. xxx., fig. 84. Rab. Stissw. Diat., 
p. 56, T.iv., fig.17. Ralfs, im Pritch., p. 786. Grunow, Verhand. der 
K. K. Zool. Bot. Gesel., Band xii., 1872, p. 392. Heiberg, De Danske 
Diat., p. 65, who considers it a brackish water form. 
River Erne, Crossdoney, Co. Cavan. Caum Lough, near Tralee. 
Pedler’s Lake, Dingle, Co. Kerry. Kailcool, Co. Wicklow. Stream, 
Fintragh, Co. Donegal. 
Var. gracilis, (Wm. Sm.) Fresh water. 
This variety differs from the preceding only in not being con- 
stricted at the ends, and the stipes being short, the frustules scattered 
and not arranged in the form of a fan. In identifying this species we 
can go no further back than the date of Smith’s work, in which it is 
faithfully delineated. Kiitzing’s figures of the species named Syn. 
gracilis are so indistinct that it would be impossible to identify them 
with certainty. (Pl. 28, fig. 18.) 
ymedra gracilis, Wm. om’ B."1)., Vol. 1; p. 70, Pl. x1.) fig. 85. 
Ralfs, in Pritch., p. 786, who describes the form as marine. Rab. 
Fl. Eur., sect. 1, p. 182, where the form is stated to be submarine, in 
which the author coincides with Smith.—Synedra fasciculata, Kiitz. 
—Synedra saxonica, Kiitz, according to Grunow, Verhand. der K. K. 
Zool. Bot. Gesel., Band xii., p. 391. Cleve regards this species as 
incidental to brackish water, and with Grunow considers it identical 
with Synedra fasciculata, Kiitz, Om Svenska och Norska Diat., p. 220. 
Stream, Port-na-Crush, Co. Donegal. Carnlough, Co. Antrim. 
