O'Meara — Rej)ort on the Irish Biatomacece. 257 



and a portion of the only gathering he ever made of it (near Paris.)" 

 Q. J. M. S., Oct., 1860, p. 245. Subsequently De Brebisson found the 

 same form at Falaise, and gave a figure of it which is confirmatory of 

 the opinion of Walker-Arnott. " !Notes on some French Diatomacese," 

 Journal of Queckett Mic. Club for April, 1870, fig. 6. Kiitzing states 

 that this species is adnate. I have never seen it so. 



Kiitz. Bac, p. 50, T. xxx., fig. 68. Eab. Siissw. Diat., p. 11. 

 T. ii., fig. 2. Possibly this species may be identical with C. Kiitzin- 

 giana, var. B. "Wm. Sm., B. D., Vol. i., p. 27 ; and if so, it is not the 

 same that Balfs has figured as C. rectangula (De Breb.) Ealfs, in 

 Pritch., PI. v., fig. 54 ; the latter being undulate on the front view, 

 whereas the present species is rectangular. 



Lucan. Peather-bcd mountain, Co. Dublin. Kilcool, Co.Wicklow. 



Cyclotella operculata, (Kiitz.) Presh water. 



Marginal striae short, fine, linear ; central part of valve covered 

 with distinct moniliform strife radiately arranged. (PL 26, fig. 12.) 



Though Smith, who is followed by Balfs, describes the strise in 

 this species as obscure and very short, the figure in both cases is too 

 clear to admit of any doubt as to identification. 



Kiitz. Bac, p. 50, T. i., figs. 1, 12, and 15. Wm. Sm., B.D., 

 Vol. i., PI. v., fig. 48. Ealfs, in Pritch., p. 811, PI. v., fig. 53.— 

 Orthosira operculata, Heiberg, De Danske Diat., p. 32. Cleve, Om 

 Svenska och Norska Diat., p. 217. This form is not identical with 

 that described by Walker- Arnott under this name, with the centre 

 destitute of striae, but probably is the same as the variety he identifies 

 with C. minutula, Kiitz. See Arnott on Cyclotella, Q. J. M. S. for 

 Oct., 1860, pp. 246, 247. 



Lower Lake, Killarney, Co. Kerry. Derrylane Lake, Co. Cavan. 

 Glenchree, Co. Wicklow. Piver Bann, near Coleraine, Co. Derry. 

 Eiver Erne, Crossdoney, Co. Cavan. Eoyal Canal, Enfield, Co. Meath. 

 Lough Neagh, near Lurgan, Co. Armagh. Lough Mourne deposit. 

 Lough Tsland-Eeavy deposit, found also living in the same place. 



Cyclotella operculata, var. Eresh water. 



Margin of valve fringed with short rounded distinct costae, over 

 which there is a circle of very fine linear striae, short ; centre of the 

 valve as in the former, but the moniliform striae much finer and more 

 obscure. (PI. 26, fig. 12, b.) 



On banks of the Litfey, near Ballymore Eustace, Co. Kildare. 

 Lough jSTeagh, near Lurgan, Co. Armagh. 



Cyclotella antiqua, (Wm. Sm.) Eresh water. 



Marginal portion of the valve narrow, marked with short, broad, 

 triangularly formed bars, over which there is a circlet of very fine 

 short linear striae ; central portion occupied by about nine triangular 

 bars which do not reach the centre. (PI. 26, fig. 13.) 



