O'Meara — Report on the Irish Diatomacece. 383 



(h) Fmcatce. 



Valves more or less elliptical ; strice divided into tivo portions on each 

 ■side of the median line, ly two longitudinal sulci, forming a tolerably 

 iroad rhomhoidal space ahout the median line. 



Navicula fusca, (Gregory). Marine. 



Valve oblong elliptical ; strise obviously moniliform, radiate ; inter- 

 mediate space lanceolate, divided into three compartments, one unstri- 

 ate, and having the median line in the centre, and one on either side 

 striate ; central nodule large ; length about •0047, breadth about 

 •0022. (Plate 32, fig. 17.) 



Ealfs, in Pritch., p. 898 ; Eab. M. Eur. Alg., sect, i., p. 179. 

 Donkin, N. H. Brit. Diat., p. 7, PL i., fig. 5. — ISTavicula Smithii var. 

 fusca, Gregory, Diat. of Clyde, p. 486, PI. ix., fig. 15. Schmidt's 

 Atlas der Diat., T. vii., fig. 1. 



Arran Islands ; stomachs of Ascidians, Eoundstone Bay ; stomachs 

 of Ascidians, Broadhaven, Co. Galway. Bostrevor, Co. Down. 



Navicula smithii, (De Breb.) Marine. 



Valve broadly elliptical ; striae monilif orm, slightly radiate ; inter- 

 mediate space narrow, lanceolate, consisting of three distinct por- 

 tions, one unstriate about the median line, and one on either side of the 

 latter striate; length about '0027, breadth about -0012. (Plate 32, 

 fig. 18.) .. . • 



"Wm. Sm., B. D., Vol. ii., p. 92. Smith assents to the suggestion of 

 DeBrebisson, to change to Navicula smithii the form he had previously 

 named jS'avicula elliptica, B. D., Vol.i., p. 48, PL xvii., fig. 152. Porthis 

 reason Grunow, Heiberg, and Donkin rightly attribute the species to 

 De Brebisson. Grunow, Verhand. der K. K. Zool. Bot. GeselL, Band 

 X., 1860, p. 531. Heiberg, De Danske Diat., p. 81. Ealfs, in 

 Pritch., p. 898. Eab. PL Eur. Alg., sect, i., p. 178. Donkin, I^. H. 

 Brit. Diat., p. 6, PL L, fig. 4. Schmidt's Atlas der Diat., T. \\\., 

 fig. 16. 



Arran Islands ; Stomachs of Ascidians, Eoundstone Bay ; Sto- 

 machs of Ascidians, Broadhaven Bay, Co. Galway. Eostrevor, Dun- 

 drum Bay, Co. Down. Bannow, Co. Wexford. Seaweeds, Kilcool, 

 Co. Wicklow. 



Var. subrotunda, (O'Meara). Marine. 



Like the typical species, but nearly orbicular. 



Schmidt's Atlas der Diat., T. vii., fig. 17, fig. 22? 



Stomachs of Ascidians, Eoundstone Bay; Arran Islands, Co. Gal- 

 way. 



