O'Meara — Report on the Irish Diatomacece. 351 



avoid confasion, the specific name adopted by Ehrenberg and Kiitzing 

 for this species had best be abandoned, and the designation proposed 

 by Gruno-^" as above substituted for it. 



Eaphoe, Co. Donegal. Lough iN'eagh, near Lurgan, Co. Armagh. 

 +3ub-peat deposit, Dromore, Co. Down. 



Navicula hacillum, (Ehi\) Fresh water. 



Valves linear ; ends rounded ; costae fijie, strongly marked in the 

 middle, radiate ; intermediate free space narrow, slightly expanded in 

 the middle; length about -0018, breadth about -0005. (Plate 30, 

 £g. 29.) 



Ehrenberg has given many figures of a species so named, some of 

 which are utterly undistinguishable ; one from a marine habitat in- 

 dicated cannot be the same. Two, however, of his figures are plain 

 •enough for satisfactory identification. 



Ehr. Mic. T. xv., A. fig. 38 ; T. ii., 2. fig. 14. Kiitz. Bac, p. 96, 

 T. xxviii., fig. 69. Wm. Sm., B.D., Yol. ii., p. 91. Ealfs, in Pritch., 

 p.". 907. Gutmow, Yerhand. der K. K. Zool. Bot. Gesell., Band x., 

 1860, p. 551, T. iv., fig. 1. Eab. Siissw. Diat., p. 39, T. vi., fig. 76. 

 Seiberg, De Danske Diat., p. 85. 



Ditch near town of "Wexford. Lower Lake, "Killamey, Co. Kerry. 

 Lough N'eagh, near Lurgan, Co. Armagh. Cushendun, Co. Antrim. 

 Derrylane Lough, Co. Cavan. Sub-peat deposit, Dromore, Co. Down. 

 Lough ]\rourne deposit. 



Navicula americana, (Ehr.) Eresh water. 



Yalve linear, oblong, with rounded ends; length '0035, breadth 

 '0010; slightly constricted; costse fine, convergent in the middle, and 

 nearly parallel towards the ends; intermediate free space wide, greatly 

 expanded in the middle; central nodule large, median line very 

 strongly marked. (Plate 30, fig. 30.) 



Ehr. Hie. T. II., n., fig. 16. Kitton, Science Gossip, June, 1868, 

 p. 131. 



This species in a fossil state is widely dispersed; besides the 

 locality indicated by Ehrenberg, it has been found by Mr. Kitton of 

 ISTorwich, in Perley's Meadow deposit, Sth. Bridgton, Maine, TJ. S. A. 

 I found it in great abundance in a fresh water deposit discovered by 

 Dr. Moss, R. N"., in Yancouver's Island, as also in a sub-peat deposit 

 from Dromore, Co. Down. Rev. George Davidson has furnished me 

 with specimens found in a fossil state in Lough Canmore, near Aber- 

 deen. I have found it in tolerable abundance in a living state in 

 Lough IS'eagh, near Lurgan, Co. Armagh. 



Navicula isocephala, (Ehr.) Freshwater. 



Yalve long, narrow; length -0055, breadth -0007; undulate on the 

 margin, with three nearly equal and slight inflations ; ends constricted 



