O'Meara — Report on the Irish BiafomacecB. 371 



Navicula maxima, (Grregory). Maiine. 



Prustules on front view slighly constricted in the middle, rounded 

 at the ends ; valve linear, ends rounded ; transverse striae fine, linear, 

 parallel ; longitudinal striae two or three ; intermediate free space 

 narrow, slightly expanded in the middle ; leng-th about '0050, breadth 

 about -0011. (PI. 31, fig. 38.) 



Gregoiw, Q. J. M. S., 1855, p. 41, PL iv., fig. 10. Ralfs, in 

 Pritch., p.^'gOQ, PI. vii., fig. 75. DonMn, ^^. H. Brit. Diat.— The last 

 named author regards this species as identical withjS^aviculabicuneata, 

 Grunow. There is certainly a strong resemblance between the two 

 forms in many particulars, biit nevertheless they seem to me perfectly 

 distinct. iS^avicula bicuneata is much broader, ever constricted, some- 

 times veiy much so, but one longitudinal sulcus is noticeable in it, 

 whereas in Xavicula maxima the longitudinal lines are more nume- 

 rous, and not so distinctly marked. Eab. Fl. Eur. Alg., sect, i., p. 172. 



Portmarnoek, Ireland's Eye, Co. Dublin. Breaches near I^ewcas- 

 tle, Co. Wicklow. Seaweeds, Kilkee. Stomachs of Ascidians, Co. 

 Clare. 



Var. linearis, (Grunow). Marine. 



Yalve much narrower and shorter than the typical form, trans- 

 verse striae finer ; longitudinal striae obvious ; intermediate free space, 

 narrow, not expanded in the middle; length "0032; breadth "0005. 

 (PI. 31, fig. 39.) 



Navicula linearis, Grunow, Yerhand. der K. K.Zool. Bot. Gesell., 

 Band x., 1860, p. 546, T. iii., fig. 2. Eab. Fl. Eur. Alg., sect, i., 

 p. 180. 



Stomachs of Ascidians, Co. Clare. Stomachs of Ascidians, Eound- 

 stone Bay. Arran Islands, Co. Galway. 



Var. lata, (O'Meara). Marine. 



Valves as in the typical form, but relatively shorter and wider, the 

 ends somewhat cuueate ; length -0030; breadth 'OOIO. 



Stomachs of Ascidians, Co. Clare. 



Navicula siibida, (Kiitz.) Marine. 



Yalve lanceolate, transverse striae very obscure, longitudinal, ob- 

 vious ; the dry valve pale straw-colour ; intennediate free space very 

 narrow; length about -0024 ; breadth about -0004. (PL 31, fig. 40.) 

 Kiitz. Bac, p. 91, T. xxx., fig. 19. Grunow, Yerhand. der K. K. 

 Zool. Bot. GeseU., Band x., 1860, p. 548, T. iii., fig. 24. Eab. Fl. Eur. 

 Alg., sect, i., p. 175. The specimens I have met with are much 

 shorter than that figured by Kiitzing, and agree with the figui-e of 

 Grunow. 



Stomachs of Ascidians, Co. Clare. Stomachs of Ascidians, Eound- 

 fitone Bay, Co. Galway. Malahide, Co. Dublin. 



