O’Mrara—Report on the Irish Diatomacee. 369 
Navicula undosa, (Ehr.) Fresh water. 
Valve broadly elliptical, slightly triundulate; apices produced, 
very narrow, and slightly capitate; longitudinal striz distinct ; trans- 
verse striz obscure; length -0016, breadth :0006. (Plate 31, fig. 32.) 
Kiitz. Bac., p. 101, T. xxvii., fig. 83. Rab. Stissw. Diat., p. 41, 
Bi ves fie. 56. 
River Erne, near Crossdoney, Co. Cavan. 
Navicula esox, (Ehr.) Habit. doubtful. 
Valve lanceolate, with an angular expansion in the middle; margin 
slightly triundulate; ends cuneate; strie distinct, linear, punctate, 
nearly parallel in the middle, shghtly radiate and closer towards the 
ends; median line strongly developed; terminal nodules at some dis- 
tance from the ends; length ‘0034, breadth -0010. (Plate 31, 
fig. 33.) 
Kiitz. Bac., p. 94, T. xxvin., fig. 53, who regards the species as 
identical with Pinnularia esox, Ehr. Ralfs, in Pritch., p. 896, Pl. 
xil., fig. 43. The description in this case is tolerably accurate, but 
the figure is incorrect.—Pinnularia esox, Rab Stssw. Diat., p. 45, 
T. vi., fig. 7. This figure does not at all represent the pecularities 
of the species. 
It is doubtful whether this is a fresh-water or marine form. 
Rabenhorst includes it among the former; the only gathering in which 
I found it was marine, yet containing some fresh water forms. _ 
Mud from salt water, coast of Clare, supplied by Doctor Sullivan, 
President Queen’s College, Cork. 
Nawicula trochus, (Ehr.) Fresh water. 
Valve inflated in the middle, greatly contracted towards the ends, 
which are slightly capitate; transverse strie indistinct; longitudinal 
strie distinct; imtermediate free space narrow, except in the middle, 
where itis expanded. (Plate 31, fig. 34.) 
Kutz. Bac, p. 99, T.im., fig. 59.  Ralfs, im Pritch., p. 899.— 
Navicula follis, Donkin, N. H. Brit. Diat., p. 44, Pl. vi., fig. 15. 
There is considerable difficulty as to the synonymy of this species. 
Donkin considers it identical with Navicula follis, Ehr., Navicula crux, 
Ehr., and Navicula inflata, Kitz. Supposing the figures of the last named 
as delineated by Kiitzing (Bac., T.111., fig. 36), and by Rabenhorst (Stssw. 
Diat., p. 41, T. v., fig. 10), to be correct, and that the former author 
was correct in supposing Navicula inflata to be identical with Navicula 
follis, Ehr., I cannot think that the latter is likely to be identical 
with Navicula trochus. Kiitzing has figured Navicula trochus so accu- 
rately, that it is easily recognisable; it is identical with that under 
consideration, and also, as it appears to me, with that named Nayicula 
follis, by Donkin. 
Lough Mourne deposit. 
