378 Proceedings of the Royal Iriah Academy, 



tre, where it expands considerably ; expanded area somewliat rounded ; 

 striae monilif orm, conrergent in the middle, then strongly radiate ; 

 length -0035 ; breadth -0017. (Plate 32, fig. 2.) 



Dentin, Q. J. IT. S., 1858, p. 17, PI. ui., fig. 19, who attributes 

 the species to De Brebisson. Ealfs, in Pritch., p. 903. Cleve, Om 

 Svenska och IS'orska Diat., p. 226. Ptab. El. Eur. Alg., sect, i., p. 

 201. Donkin, N. H. Brit. Diat., p. 17, PI. iii., fig. 1. 



Drehednamaud, near Castlegregory, Co. Kerry. Stomachs of As- 

 cidians, Roundstone Bay, Stomachs of Ascidians, Broadhaven Bay, 

 Galway Bay, Co, Galway. 



Navicula humerosa, (De Brebisson.) Marine. 



Yalve linear, elliptical, gradually contracted towards the broad, pro- 

 duced, rounded ends ; slightly constricted in the middle ; strise close, 

 moniliform ; puncta small, convergent in the middle, radiate towards 

 the ends ; intermediate free space narrow, except in the middle, where 

 it is broadly and somewhat roundly expanded ; length, about -0032, 

 breadth, about -0013, and in middle about -9012. (Plate 32, fig. 3.) 



Wm. Smith, (B. D., Yol. ii., p. 93), who attributes the species to 

 De Brebisson. Ealfs, in Pritch., p. 903. Eab. PL Eur. Alg., sect, i., 

 p. 201. 



Bannow, Piyer Slaney, near Xillurin. Co. Wexford. Portmar- 

 nock, llalahide, Co. Dublin. Seaweeds, Portrush, Co. Antrim. 

 Caum Lough, near Tralee, Lough Gill, Co. Keny. Ealkee, Co. 

 Clare. Salt marsh, Kileool, Co. "Wicklow. 



Var. fuscata, (Schumann). Marine. 



Like the typical form, but having the ends slightly capitate, and 

 the margins perfectly linear; length -0038, breadth -0014. (Plate 32, 

 fig. 4.) 



Likely the same as Navicula fuscata, Schumann, Die Preussische 

 Diat., p. 57, T. ii., fig. 43. 



Drehidnamaud, near Castlegregory : Lough Gill, Co. Kerry. 

 Stomachs of Ascidians, Roundstone Bay, Co. Galway. 



Var. quadrata, (Gregory). Marine. 



Like the typical form, but much shorter and relatively broader ; 

 the margins linear ; the ends, too, being broader and less produced ; 

 length -0020, breadth -0012. (Plate 32, fig. 5.) 



Navicula quadrata, Gregory, Q. J. M. S., 1856, p. 41, PI. v., fig. 5. 

 Donkin (N. H.Brit. Diat., p. 18) considers this identical with I*^avicula 

 humerosa, and Ralfs adopts the same opiEion in Pritchard, p. 903. 



Lough Gni, Co. Kerry. Stomachs of Ascidians, Broadhaven Bay, 

 Co. Galway. Seaweeds, Portrush, Co. Antrim. 



