O'Meara — Report on the Irish Biatomaccce. 30& 



dency towards the elliptical outline, I am disposed to regard these as 

 abnormal, the normal character being linear. Smith indeed distin- 

 guishes the two forms by the fact that, in the latter, the frustules 

 are loose and scattered, whereas in the former they are arranged 

 radiately ; and, although such a feature of growth is not to be wholly 

 overlooked, it is scarcely sufficient to distinguish the species, especially 

 in the earlier stages of growth, where the frustules are few in number. 

 I am inclined to think the form which Smith describes as Synedra 

 ulna is really Synedra splendens. It seems strange that this form 

 should have been attributed to Wm. Smith, although he regards what 

 he calls Synedra radians as equivalent to Synedra splendens, Kiitz. 



Kiitz., Bac, p. 66, T. xiv., fig. 16 ; Eab. Sussw. Diat., p. 54, 

 T. iv., fig. 4 ? E,alfs, in Pritch., p. 788. Grunow, Yerhand. der K. K. 

 Zool. Bot. Gesel., Bandxii., p. 394. — Synedra radians, Wm. Sm., B.D., 

 Yol. i., p. 71, PI. x.i., fig. 89. Heiberg, De Danske Diat., p. 64. 

 Castracane, Catalogo di Diat. raccolte nell Yal Intrasca, p. 10. Cleve^ 

 Om Svenska och JS'orska Diat., p. 220. 



Stream, Crossdoney. Derrylane Lough, Co. Cavan. Lacan. 

 Friarstown, Bohernabreena, Malahide, Co. Dublin. Tacumshane, Co. 

 "Wexford. Killeshin, Queen's Co. Royal Canal, Enfield, Co. Meath. 

 Glencar. Pedlar's Lough, near Dingle, Co. Kerry. Ditch near railway 

 station, Dundalk, Co. Louth. River Suck, Ballinasloe, Co. Galway. 



Var. radians, (Kiitz.) Presh water. 



Like the tvpical species, but smaller, and the ends more acute on 

 side view. (PI. 28, fig. 30.) 



Kiitz. Bac, p. 64, T. xiv., fig. 7. Ralfs, in Pritch., p. 787.— Syne- 

 dra radians, Wm. Sm., B. D., Yol. i., p. 71, PL xii., fig. 89 B, 

 and 89 y. 



Priarstown, Co. Dublin. Derrylane Lough, Co. Cavan. Pedlar's 

 Lough, near Dingle, Co. Kerry. Ditch near Dundalk, Co. Louth. 

 Ditches in the Callows, Ballinasloe, Co. Galway. 



Var. danica, (Kiitz.) Presh water. 



Prustules longer and narrower than the typical species, the stria- 

 tion finer, and the valves on front view more gradually attenuated 

 towards the ends, which are broadly rounded off, and not capitate.. 

 (PL 28, fig. 31.) 



Kiitz. Bac, p. 66, T. xiv., fig. 13.— Ralfs, in Pritch., p. 788; 

 Synedra radians var. debilis, Rab. PI. Eur., sect. 1, p. 134 ? Grunow 

 considers this var. = Synedra radians, Wm. Sm., B. D., Yol. i., p. 71, 

 PL xii., figs. 89 B, and 89 y ; Yerhand. der K. K. Zool. Bot., Gesel., 

 Band xii., p. 396 ; but Synedra danica is much longer than that 

 variety, less lanceolate, and with broader rounded apices. 



River Moy, near Poxford, C. Mayo. Bantry Well, Parraghy, Co. 

 Cork. Donoughmore, Co. Tyrone. Coolnamuck, parish of Dysert, Co^ 

 Waterford. 



