O'Meara — Beport on the Irish Diatomacem. 347 



thicker striation of tlie former species." Yerhand. der K. K. Zool. 

 Bot. Gesell., Band x., 1860, p. 516. — !N'avicula acrosphseria. De Bre- 

 bisson, Consid. siir les Diat., 1838, p. 19. Dentin, N. H. Brit. Diat., 

 p. 72, PI. xii., fig. 2. — Pinnnlaria acrosphseria, "Wm. Sm., B. D., 

 Vol. i,, p. 58, PL xis., fig. 183. — Pinnnlaria tabellaria, var. acrosphse- 

 ria, Eab. PL Enr. Alg., sect, i., p. 211. 



Carnew, Greenane, Co. "Wicklow. Lake near Castlewellan, Co. 

 Down. Camolin, Co. "Wexford. 



(b.) GilhoscB. 



Similar to the NoMles; the s f rice finer ; the intermediate free space 

 narroioer, expanding aroxmd the central nodule, and sometimes extending 

 to the margin in a stauriform hand, 



Navicula clepsydra, (Donkin). Marine. 



Pmstnles on front view constricted in tbe middle ; ends angular ; 

 side view largely apparent. Yalves narrow, elliptical ; ends rounded. 

 Length about -0040 ; breadth about -0009. Striae 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.) 



Donkin, Q. J. M. S., 1857, p. 8, PL i., fig. 3. Do., K H. Brit. 

 Diat., p. 63, PL x., fig. ii. Eab. Fl. Eur. Alg., sect, i., p. 181. 



Ireland's Eye, Co. Dublin. 



Navicula nipestris, N". S. Fresh water. 



Yalve in length '0025 ; breadth -0008 ; linear, elliptical, very 

 gently attenuated towards the rounded ends. Strise 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 a rhomboid form. (PL 30, fig. 17.) 



Found on moist rock, Portrush, Co. Antrim. 



Navicula ceres, (Schumann). Marine. 



Yalve linear, elliptical ; gently attenuated towards the rounded 

 ends. Length -0022 ; breadth -0007. Striae 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 !N"achtrag, p. 56, T. ii., 

 fig. 38. 



Stomachs of Ascidians, Broadhaven Bay, Co. Galway. 



R. I. A. PllOC, SER. II., VOL. II., SCIENCE. 2 R 



