O'Meara — Report on the Irish Diatomacece. 295 



RJiwphoneis amphiceros, (Ekr.) Marine. 



On side yie"V7 Yalves short, broadly rhomboid; yery slightly pro- 

 duced at the apices; striae large, moniliform, radiate; median free space 

 linear, and very narrow, so much so as to be sometimes scarcely dis- 

 cernible ; fr"ustules stipitate. (PI. 28, fig. 3.) 



Ealfs. in Pritch., p. 791, PL xiv., fig. 21. Eab. Fl. Eur., sect. 1, 

 p. 126. — Doiyphora amphiceros, Kiitz. Bac, p. 74., T. xxi., fig. 2. 

 Wm. Sm., B. D., Yol. i., PL xxiv., fig. 224. Grunow, Yerhand der 

 K. K. Zool. Bot. GeseL.Band sii., 1862, p. 384. 



From mud on sea-shore, Co. Clare, supplied by Professor Sullivan. 

 On Sea- weeds, Co. Clare. On Sea-weeds, Co. Donegal. 



Var. leptoeeros, (Ehr.) Marine. 



Similar in all respects to Ehaphoneis amphiceros, but longer, nar- 

 rower, and the ends produced into long beaks. 



Phaphoneis leptoeeros, Palfs, in Pritch., p. 791. 



Sea-weeds, Co. Donegal ; sea-weeds, Co. Clare, 



Rhaphoneis rhombus, (Ehr.) Marine. 



Yalves narrow, elliptical ; ends rounded, striae fine ; moniliform ; 

 parallel in the middle, and slightly radiate towards the ends ; median 

 unstriate space narrow, linear in the middle, and expanding towards 

 the ends. 



Ealfs, in Pritch, p. 792. Grrunow, Yerhand der K. K. Zool. Bot. 

 GeseL, Band xii., 1862, p. 379, T. iv., fig. 36. Eoper, Q.J. M.S., 

 Trans., YoL ii., 1854, PL vi., figs. 7-10. 



Concerning this form, Gmnow, as above cited, makes the following 

 noteworthy remarks: — ''Ehaphoneis rhombus ought to be considered 

 as the type of the genus Ehaphoneis, which must ever stand, though 

 other species be separated as not belonging to it. The frustules in 

 contradistinction to Doryphora occur free, as I consider I have satisfied 

 myself to be the case." 



Sea- weeds, Dundalk, Co. Louth. Piles of the wooden bridge, 

 Dollymount, Co. Dublin. Sea-weeds, Co. Donegal. 



A smaller variety occurs frequently in the last named gathering, 

 much broader for the length than the ordinary specimens, but in other 

 respects so similar that it cannot be considered even a variety. 



Rhaphoneis scutelhides, (Grunow.) Marine. 



Yalves small, on front view broadly elliptical, rounded at the ends, 

 stirse obscurely moniliform, nearly parallel at the middle, and slightly 

 radiate towards the ends ; median free space, narrow, elliptical. (PL 

 28, fig. 4.) 



Grunow, Yerhand der K. K. Zool. Bot. GeseL, Band xii., 1862, p. 

 383, T. iv., fig. 34. 



Sea-weeds, Co. Donegal. 



