O’Mrara—Report on the Irish Diatomacee. 347 
thicker striation of the former species.”” Verhand. der K. K. Zool. 
Bot. Gesell., Band x., 1860, p. 516.—Navicula acrospheria. De Bré- 
bisson, Consid. sur les Diat., 1838, p. 19. Donkin, N.H. Brit. Diat., 
p. 72, Pl. xu., fig. 2.—Pinnularia acrospheria, Wm. Sm., B. D., 
Vol. i., p. 58, Pl. xix., fig. 183.—Pinnularia tabellaria, var. acrosphe- 
ria, Rab. Fl. Eur. Alg., sect. 1., p. 211. 
Carnew, Greenane, Co. Wicklow. Lake near Castlewellan, Co. 
Down. Camolin, Co. Wexford. 
(b.) Gibbose. 
Similar to the Nobiles; the strie finer; the intermediate free space 
narrower, expanding around the central nodule, and sometimes extending 
to the margin in a staurvform band, 
Navicula clepsydra, (Donkin). Marine. 
Frustules on front view constricted in the middle; ends angular; 
side view largely apparent. Valves narrow, elliptical; ends rounded. 
Length about :0040 ; breadth about :0009. Striz punctate, converg- 
ing in the middle; slightly radiate towards the ends; intermediate 
free space linear, narrow, except in the centre, where it is roundly 
expanded. (Plate 30, fig. 16.) 
Donkam, Gs. Mw8:, W657, p.-S, Pioa., fesss “Do. NN. Bl but 
Diat., p. 63, Pl. x., fig. u. Rab. Fl. Eur. Alg., sect. i., p. 181. 
Treland’s Eye, Co. Dublin. 
Navicula rupestris, N.S. Fresh water. 
Valve in length -0025; breadth -0008; linear, elliptical, very 
gently attenuated towards the rounded ends. Striz costate, fine, 
waved, converging in the middle, radiate towards the ends; interme- 
diate free space narrow, except in the middle, where it is expanded 
in arhomboid form. (Pl. 30, fig. 17.) 
Found on moist rock, Portrush, Co. Antrim. 
Navicula ceres, (Schumann). Marine. 
Valve linear, elliptical; gently attenuated towards the rounded 
ends. Length -0022; breadth 0007. Strie costate, in some lights 
appearing as if closely moniliform ; convergent in the middle; slightly 
radiate towards the ends; intermediate free space narrow, except in 
the middle, where it is greatly expanded. (Pl. 30, fig. 18.) 
Schumann, Preussische Diatomeen; Zweite Nachtrag, p. 56, T. ii., 
fig. 38. 
Stomachs of Ascidians, Broadhaven Bay, Co. Galway. 
R. I, A. PROC., SER, II., VOL. II., SCIENCE. 2R 
