370 - Proceedings of the Eoyal Irish Academy. 



Navicula prodiicta, (^va.. %vli.) Fresh. -n-ater. 



Talve linear^ elliptical ; ends produced and slightly capitate ; 

 transverse stris distinct ; linear-pnnctate parallel ; longitudinal striae 

 distinct ; intermediate free space very narrow ; lenailL "0040, breadth 

 •0010. (Plate 31, fig. 35.) 



ATm. Sm., B.D., Yol. i., p. 51, PL xvii., fig. 144. Ealfs, in 

 Pritch., p. 902, PI. rii., fig. 62. Grimow, Yerhand. der K. K. Zool. 

 Bot. Gesell., Band x., 1860, p. 543. — Xayicula affinis, rar. producta, 

 Rah. Fl. Eur. Alg., sect, i., p. 197. 



Botanical Gardens of Trinity College, Dublin. Lower Lake, Eillar- 

 ney, Co. Eerry. Sub-peat Deposit, Droraore, Co. Down. 



JSFavicida coccononeiformis, (Gregory). Fresh water. 



Yalre elliptical ; transverse strife very fine, linear slightly radiate ; 

 longitudinal stride more obvious ; intermediate free space naiTOW, 

 lanceolate; length -0016, breadth -0008. (Plate 31, fig. 36.) 



Xone of the authors I am acquainted with have alluded to tbe 

 longitudinal striae, which notwithstanding are very obvious when the 

 valve is observed in a dry state. "Wlien mounted in balsam, they are 

 quite undistinguishable, except with very high powers, and with good 

 illumination. 



Gregory, Q. J. M. S., 1856, p. 6, PI. i., fig. 22. Wm. Sm., B.D., 

 Yol. ii., p. 92. Ealfs, in Piitcb., t). 896. Grunow, Yerhand. der 

 . K. K. ZooL Bot. GeseU., Band x., 1860, p. 550, T. iv., fig. 9. Bab. 

 Fl. Eur. Alg., sect. 1, fig. 186 and p. 189. Donkin, ^". H. Biit. Diat., 

 p. 22, PL iii., fig. 11. Lagerstedt, Sotv. Diat. fran Spetsbergen och 

 Beeren Eiland, p. 32, T. ii., fig. 8. 



Lough Mask, near Toumakeady, Co. llayo. Lough Mourne 

 deposit. 



Naviexda Koizcliyi, (Grunow). Fresh water. 



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

 occasionally slightly constricted ; central nodule large and quadrangu- 

 lar ; strife fine, linear, in the middle more distinct than towards the 

 ends, radiate; longitudinal stiiaj distinct ; length '001 3, breadth "0005. 

 Grunow, Yerhand. der K. K. Zool. Bot. Gesell., Band x., 1860, 

 p. 538, T. iv., fig. 12. This author represents the striae as moniliform, 

 but in the few forms that came under my notice I could not verify 

 this representation. The longitudinal strife are not noticed by Grunow, 

 but with careful manipulation they were very apparent in my speci- 

 mens. Grunow gives three figui'es of this species ; of these the short- 

 est and broadest, and that in which the striae are not so distinct is the 

 form with which my specimens are most in accordance. — Xavicula 

 Kotschyana, Eab. FL Eur. Alg.. sect, i., p. 193. 



Lough Mask, near Tounnakcady, Co. Mayo. 



