398 Proceedings of the Royal Irish Academy. 
Navicula donkinia, (O’Meara). Marine. 
Valve slightly constricted; ends somewhat cuneate, rounded; 
median compartment narrow, slightly inflexed at the ends, slightly 
constricted in the middle; compartments at either side narrow, arcu- 
ate, having very faint strie; marginal striate band narrow; stri«e 
costate, coarse, sub-distant; nearly parallel in the middle, slightly 
radiate towards the ends; length ‘0015, breadth at the constriction 
‘0006; greatest breadth 00066. (Plate 33, fig. 20.) 
Schmidt, Atlas, T. xu., fig. 63.—Navicula musca, Donkin, N. H. 
Brit. Diat., p. 50, Pl. vii., fig. 6, exclusive of Synonyms. 
Arran Islands; Stomachs of Ascidians, Roundstone Bay; Sto- 
machs of Ascidians, Broadhaven Bay, Co. Galway. 
Navicula marginata, (O’Meara). Marine. 
Valve very slightly constricted; median compartment broad, shghtly 
inflexed at the ends, slightly expanded in the middle; compartments 
at either side nearly linear; striz extremely faint; marginal striate 
band narrow ; strie costate, not reaching the margin, nearly parallel ; 
length :0036, breadth 0011. (Plate 33, fig. 21.) 
Pinnularia marginata, O’Meara, Q.J.M.8., 1869, p. 15, Pl. xu, 
fig. 4, 
Arran Islands; Stomachs of Ascidians, Broadhayen Bay; Sto- 
machs of Ascidians, Roundstone Bay, Co. Galway. 
Navicula subcincta, (Schmidt). Marine. 
Valve large, slightly constricted, ends somewhat cuneate, rounded ; 
median compartment broad, inflexed at the ends, slightly constricted 
in the middle; compartments on either side broad, unstriate ; marginal 
striate band divided into two equal portions by a longitudinal sulcus ; 
striz costate, close, parallel in the middle, slightly radiate towards the 
ends; length ‘0042, breadth at the constriction -0015; greatest 
breadth, -0016. (Plate 33, fig. 22.) 
Schmidt, Biolog. Untersuch. der Nordsee. Diat., p. 87., T. x1., fig. 7. 
Arran Islands. Stomachs of Ascidians, Broadhayen Bay, Co. Gal- 
way- 
Nawicula archeriana, N.S. Marine. 
Valve large, slightly constricted ; ends somewhat cuneate, rounded ; 
median compartment broad, inflexed at the ends, constricted in the 
middle; compartments at either side broad, arcuate; marginal striate 
band narrow ; striz costate, parallel in the middle, radiate towards the 
ends; length ‘0026, breadth :0012; at constriction, ‘0011. (Plate 
33, fig. 23.) 
O’Meara, Q. J. M.S., 1874, p. 260, Pl. vii., fig. 9—Navicula don- 
