O’Meara—Report on the Irish Diatomacee. 371 
Navicula maxima, (Gregory). Marine. 
Frustules on front view slighly constricted in the middle, rounded 
at the ends; valve linear, ends rounded; transverse stric fine, linear, 
parallel; longitudinal striz two or three; intermediate free space 
narrow, slightly expanded in the middle; length about -0050, breadth 
about ‘0011. (Pl. 31, fig. 38.) 
Gresory, Q d.- Mr Ses55, p. 41,° Pl cav., fig: 10.” Ralis; im 
Pritch., p. 909, Pl. vii., fig. 75. Donkin, N. H. Brit. Diat.—The last 
named author regards this species as identical with Navicula bicuneata, 
Grunow. There is certainly a strong resemblance between the two 
forms in many particulars, but nevertheless they seem to me perfectly 
distinct. Navicula bicuneata is much broader, ever constricted, some-. 
times very much so, but one longitudinal sulcus is noticeable in it, 
whereas in Nayicula maxima the longitudinal lines are more nume- 
rous, and not so distinctly marked. Rab. Fl. Kur. Alg., sect. 1., p. 172. 
Portmarnock, Ireland’s Eye, Co. Dublin. Breaches near Newcas- 
tle, Co. Wicklow. Seaweeds, Kilkee. Stomachs of Ascidians, Co. 
Clare. 
Var. linearis, (Grunow). Marine. 
Valve much narrower and shorter than the typical form, trans- 
verse striz finer; longitudinal strize obvious; intermediate free space, 
narrow, not expanded in the middle; length -0032; breadth ‘0005. 
Clo, fee.) 
Navicula linearis, Grunow, Verhand. der K. K. Zool. Bot. Gesell., 
Band x., 1860, p. 546, T: i:, fig. 2. Rab. Fl. Eur. Alg., sect. 1., 
pe leg: 
Stomachs of Ascidians, Co. Clare. Stomachs of Ascidians, Round- 
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 cuneate; length -0030; breadth :0010. 
Stomachs of Ascidians, Co. Clare. 
Navicula subula, (Kiitz.) Marine. 
Valve lanceolate, transverse strize very obscure, longitudinal, ob- 
vious; the dry valve pale straw-colour ; intermediate free space very 
narrow ; length about 0024; breadth about 0004. (Pl. 31, fig. 40.) 
Kuz. Bac. p. ot, Toxxx, fic. 19. Grunow,,. Verhand..der K. K. 
Zool. Bot. Gesell., Band x., 1860, p. 548, T.in., fig. 24. Rab. Fl. Eur. 
Alg., sect. 1, p. 175. The specimens I have met with are much 
shorter than that figured by Kiitzing, and agree with the figure of 
Grunow. 
Stomachs of Ascidians, Co. Clare. Stomachs of Ascidians, Round- 
stone Bay, Co. Galway. Malahide, Co. Dublin. 
