398 Proceedings of the Royal Irish Academy. 



Navicida donhinia, (O'Meara). Marine. 



Yalve slightly constricted ; ends somewhat cuneate, rounded ; 

 median compartment narrow, slightly in flexed at the ends, slightly 

 constricted in the middle ; compartments at either side nan'ow, arcu- 

 ate, having very faint striae ; marginal striate band narrow ; strise 

 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. xii., fig. 63. — l^avicula musca, Donkin, N. H. 

 Brit. Diat., p. 50, PI. yii., fig. 6, exclnsiye of Synonyms. 



Arran Islands ; Stomachs of Ascidians, Eoundstone Bay ; Sto- 

 machs of Ascidians, Broadhaven Bay, Co. Galway. 



Navicida marginata, (O'Meara). Marine. 



Valve very slightly constricted ; median compartment broad, slightly 

 inflexed at the ends, slightly expanded in the middle ; compartments 

 at either side nearly linear ; striee extremely faint ; marginal striate 

 band narrow ; strice costate, not reaching the margin, nearly parallel ; 

 length -0036, breadth -0011. (Plate 33, fig. 21.) 



Pinnularia marginata, O'Meara, Q. J. M. S., 1869, p. 15, PI. xii., 

 fig. 4. 



AiTan Islands ; Stomachs of Ascidians, Broadhaven Bay ; Sto- 

 machs of Ascidians, Boundstone Bay, Co. Galway. 



Navicida sidcincta, (Schmidt). Marine. 



Yalve large, slightly constricted, ends somewhat cnneate, 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 ; 

 striae 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 I^ordsee. Diat., p. 87., T. xi., fig. 7. 



Arran Islands. Stomachs of Ascidians, Broadhaven Bay, Co. Gal- 

 way. 



Navicida archeriana, 'E. S. Marine. 



Yalve 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 ; strige 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, PI. viii., fig. 9.— I^^avicula don- 



