O'Meara — Report on the Irish Diatomacece. 375 



same ; transverse striae obscure, slightly oblique ; longitudinal striae dis- 

 tinct ; length about -0038 ; breadth about -0009. (Plate 31, fig. 50.) 

 Kiitz. ^Bac, p. 92; T. xxx., fig. 23; T. xxviii., fig. 43. This 

 author considers the species identical with Frustulia serians, De Brebis- 

 son, and with Navicula lineolata, Ehr. . He adds, " I have no doubt 

 that the Ehrenbergian form, which has been described in our T. xxviii., 

 fig. 43, according to Ehrenberg, is perfectly identical with that of De 

 Brebisson." That form is rather smaller than I^avicula serians, and 

 therefore some doubt may reasonably be entertained on the subject. 

 It seems better then, with Donkin, to attribute the species to De Bre- 

 bisson than to abandon the specific name by which the species has been 

 so long known. Wm. Sm., B. D., vol. i., p. 47, PL 16, fig. 130. 

 Eab. Siissw. Diat., p. 38 ; T. vi., fig. 51 ; Kalfs, in Pritch., p. 904. 

 Grunow, Yerhand. der K. K. Zool. Bot. Gesell, Bandx., 1860, p. 549 ; 

 T. v., fig. 13. Cleve, Om Svenska och ISTor ska Diat., p. 228. Don- 

 kin, N. H. Brit. Diat., p. 41, PI. vi., fig. 10. 



Pool, Cushendun, Co. Antrim. Piperstown, Co. Dublin. Glen- 

 chi'ee, Co. Wicklow. Pool near town of Wicklow. Tollymore Park 

 deposit, Co. Down. 



JVamcuIa crassinervia, (De Breb.) Presh water. 



Yalve small, elliptical-lanceolate ; ends produced and slightly con- 

 stricted ; longitudinal sulci parallel to the median line, distinct ; striae 

 obsolete; length about -0024 ; breadth about -0005. (Plate 31, fig. 51.) 



Wm. Sm., B.D., Yol. i., p. 47, Supp. PL xxsi., fig. 271, who 

 describes and figures the species according to specimens furnished by 

 De Brebisson. Ealfs, in Pritch., p. 900. Grunow, Yerhand. der K. K. 

 Zool. Bot. GeselL, Band x., 1860, p. 548, T. v., fig. 12. Cleve, Om 

 Svenska och ISTorska Diat., p. 228. Donkin, IST. H. Brit. Diat., p. 42, 

 PL vi., fig. 12. This last named author considers this species identical 

 with Prustulia saxonica, Rab. El. Eur. Alg., sect, i., p. 227. 



Eriarstown, Piperstown, Eeatherbed Mountain, Co. Dublin. Lough 

 Gill, Co. Kerry. Bantry, Co. Cork. Eostrevor, Co. Down. Rath- 

 drum, Glencree, Co. Wicklow. 



Nmicula dirJiynchus, (Ehr.) Fresh water. 



Yalve nearly linear, narrow ; ends produced, and slightly capitate. 

 Longitudinal sulci parallel with median line, distinct. Transvei'se 

 striae obsolete; longitudinal striae distinct; length, '0022, breadth, 

 •0005. (Plate 31, fig. 52.) 



Kiitzing, Bac, p. 95, T. xxviii., fig. 48, by whom the species is 

 attributed to Ehrenberg. Rab. Siissw. Diat., p. 40, T. vi., fig. 48. 

 Ralfs, in Pritch., p. 901. Donkin, N. H. Brit. Diat., p. 29, PL v., 

 fig. 3. The last named author remarks that "in outline this species 

 has a strong resemblance to Navicula afiinis, but it is much smaller. 



