O'Meara — Report on the Iri^Ji Diatomacew. 267 



Actinoptyclnis senarius, (Ekr.) Brackish or marine. 



Yalve divicled into six compartments, areolate, areolae more or 

 less hexagonal. In this species the valves vary considerably in size. 



Ehr. Mic, T. xxi., fig. 18, a. b. Kiitz. Bac, p. 134, T. i., fig. 21, 

 T. xxi., fig. 26. The foi-m there described does not differ from that 

 which the same author has described and figni'ed as Actinocyclus undu- 

 latns, Bac, p. 132, T. i., fig. 24. Ealf s, in Pritch., p. 839, PL ix., fig. 

 132. — Actinoptychus nndulatus, Rab. Fl. Eur., sect. 1, p. 35. — 

 Actinocyclus undulatus, "^"m. Sm., B. D., Vol. i., p. 25 ; Plate v., fig. 

 43. Heib. De Danske Diat., p. 37. Cleve, Om Svenska och Ilforska 

 Diat., p. 218. 



Salt ditch near Wexford. Banno-w, Co. Wexford. Rostrevor, 

 Co. Down. Stomachs of Pectens, Dalkey. DoUymount. Portmamock, 

 Co. Dublin. Sea shore, near Ballysodare, Co. SHgo. 



Var. denarius, (Ehi-.) ilarine. 



Compartments ten in number. Ehr. Mic, T. xviii., fig. 23. 

 From stomachs of Ascidians, Roundstone Bay. ^LiTan Islands, 

 "Westport Bay, Co. Galway. 



Var. duodena ri us,. (Ehx.) ^Marine. 



Compartments twelve in number. Ehr. ITic, T. xviii. f. 24. 

 Ralfs, in Pritch., p. 840. Weisse, Bulletin de L' Academic Imp. de 

 St. Petersboirrg, Tome xii., p. 122, T, i., fig. 8. — Actinocyclus duo- 

 denarius, Wm. Sm., B.D., Yol. ii., p. 86. 



From stomachs of Ascidians, Roundstone Bay. Arran Islands, Co. 

 Gal way. 



Var. sedenarius, (Ehr.) Marine. 



Compartments sixteen in number. Ehr. ITic, T. xviii., fig. 26. 

 "Weisse, Bulletin de L'Academie Imp. de St. Petersbourg, Tome xii., 

 p. 122. T. i., fig. 9. — Actinocyclus sedenarius, "\Ym. Sm., B.D., 

 Vol. ii., p. 86. 



Sea-weeds, Bannow, Co. Y'exford. Arran Islands. From sto- 

 machs of Ascidians, Ptoundstone Bay, Co. Galway. 



Var. vicenarius, (Ehr.) llarino. 



Compartments twenty in number. The only sj)ecuncn of this 

 variety found by me has marginal teeth obvious on some of the com- 

 partments, though not noticeable on others, owing perhaps to the 

 circumstance of the valve not lying quite parallel to the side. These 

 teeth disappeared altogether when the form was mounted in balsam. 

 Ralfs, in Pritch., p. 840. Weisse, Bulletin de L'Academie Imp . 

 de St. Petersboiu'g, Tome xii., p. 122. 



Drehidnamaud, Co. KciTy. 



E.I. A. PEOC, SER. II., VOL, II., SCIENCE. 2 M 



