308 Proceedings of the Royal Irish Academy. 
Dodder, Co. Dublin. Lough Gill, Co. Kerry. Powerscourt, Co. 
Wicklow. Lough Mourne deposit. 
Navicula fulva. (Donkin). Fresh water. 
Valve very much as the preceding, but smaller, and having the 
strie somewhat radiate; length ‘0032, breadth :0007. (Pl. 31, 
fig. 2.) . 
There is great difficulty in identifying this form with that named 
Navicula fulva by Ehrenberg, which several authors identify with 
Nayicula cuspidata. 
This latter Smith has so accurately described, that there is no diffi- 
culty in identifying it, and therefore, under the circumstances, I 
attribute it to him. Donkin, too, has so figured Nayicula fulva as 
to render it equally distinctive, and for this reason I assign the 
species to him. 
Donkin, N. H., Brit. Diat,, p. 41, Pl. v1., fig. 9. 
Lough Gill, Co. Kerry. Dysart, Co. Waterford. 
Navicula cuspis, N.S. Marine. 
Valves narrow, lanceolate; length about -0044, breadth about 0008 ; 
longitudinal sulci close to median line. Striz linear, slightly radiate ; 
ends cuspidate ; dry valve a light straw colour. (Pl. 31, fig. 3.) 
From stomachs of Ascidians, Co. Clare. 
Navicula rhombiea. (Gregory). Marine. 
Frustules on front view subquadrate; slightly constricted angles, 
rounded. On side view, valve elliptical. Striz fine, lmear, converging 
in the middle, radiate ; much finer and closer towards the ends; length 
"0026, breadth -0008. (PI. 31, fig. 4. 
Gregory, Q. J. M. S., 1856, p. 38, Pl. v., fig. 1. Ralfs, in Pritch, 
p. 903. Rab. Fl. Eur. Alg..-sect.1., p.181- 
Barrow, Co. Wexford. Malahide, Co. Dublin. Lough Gill, Co. 
Kerry. Seashore near town of Galway. Breaches, Co. Wicklow. 
Stomachs of Ascidians, Belfast Lough, Co. Antrim. Stomachs of Asci- 
dians, Co. Clare. 
Navicula cerulea, N.S. Fresh water. 
Valve narrow, lanceolate: ends much produced. Length :0022, 
breadth :0005; longitudinal sulci close to median line. Strive linear, 
convergent in middle, slightly radiate towards the ends; dry valve of 
a pale colour. (Pl. 31, fig. 5.) 
Lough Mask, near Tourmakeady, Co. Mayo. 
