I 



O'Meara — Hejjort on the Irish Biafomacece. 287 



Odontidium lujemale, (Lyngb.) Fresh, "water. 



rrustules in long filaments ; valve on side vie"w narrow, elliptical ; 

 costse strong, about ten in number, with distinct linear strife between 

 the costae ; ends of costse on front view forming a narrow margin. 



Kiitz. Bac, p. 44, T. xviii., fig. 4. Eab. Siissw. Diat., p. 34, T. ii., 

 fig. 4. Wm. Sm., B.D._, Yol. ii., p. 15, PI. xxxiv., fig. 289. Ealfs, 

 in Pritch.., p. 775, PI. xiu., fig. 25. Grunow, Yerhand der K. K. Zool. 

 Bot. Gesel., Band xii., 1862, p. 356. — Diatoma hyemale, Heiberg, De 

 Danske Diat., p. 58. Cleve, Om Svenska och. IS^orska Diat., p. 219. 

 — Pragilaria hjemalis, Lyngb., Tent. Hydr. Dan., p. 63. 



"Wet rock, Black Castle, Co. "Wicklow. Streamlet near Belfast, 

 Co. Antrim. 



Odontidium mesodon, (Ehr.) Fresh water. 



Frustules united in long filaments, shorter, wider, and broader 

 than in the preceding species ; on side view broadly elliptical, with, 

 three to five strongly developed costse, which, in consequence of the 

 greater convexity of the valve, appear longer on the front than in the 

 foregoing sjiecies ; fine strife may be discovered between the costse 

 without much difficulty. (PL 27, fig. 18.) 



Heiberg attributes the species to Lyngbye, Smith to Kiitzing ; but 

 as Kiitzing him self identifies it with Fragilaria mesodon of Ehr, and 

 the Fragilaria hyemalis of Lyngbye is regarded by the same writer as 

 identical with both Odontidium hyemale and 0. mesodon, the species 

 may properly be referi'ed to Ehrenberg. 



Kiitz. Bac, p. 44, T. xvii., fig. 1. Ptab. Siissw. Diat., p. 34, T.ii., 

 fig. 2. Wm. Sm., B.D., Yol. ii., p. 16, PL xxxiv., fig. 288. Ealfs, in 

 Pritch., p. 75. — Odontidium hyemale var. mesodon, Grunow, Yerhand 

 der K. K. Zool. Bot. GeseL, Band xii., 1862, p. 357.— Fragilaria 

 mesodon, Ehr. Mic, T. ii., fig. 9, — Diatoma hyemale, Heib., De Danske 

 Diat., p. 58. Cleve, Om Svenska och IS'orska Diat., p. 219. Both 

 these last named authors regard this and the preceding^ species merely 

 as varieties. 



Friarstown, Piperstown, Co. Dublin. Glenchree, Powerscourt, 

 Co. "Wicklow. Well at Farraghy, Eiver Dour, Co. Cork. 



Odontidium anomalum, (Wm. Sm.) Fresh water. 



Filaments short ; frustules on front view usually exhibiting in- 

 ternal cells, likely the result of imperfect self-division ; on side view 

 narrow, linear, sHghtly constricted at the ends. Costse strong, about 

 eight or ten in number. 



Wm. Sm., B.D., Yol. ii., p. 16, Supp. PL Ixi., fig. 376. Ealfs, in 

 Pritch., p. 776. Grunow, Yerhand der K. K. Zool. Bot. GeseL, Band 

 xii., 1862, p. 357, T. iv., fig. 4. Eab. Fl. Eui-., sect. 1, p. 116. 



Ditch near Newcastle, Co. "Wicklow. This form is usually found 

 in Alpine districts. 



