412 Proceedings of the Royal Irish Academy. 



PI. viii., fig. 2. — PiniLularia inflexa, Gregory, Q. J. M. S., 1856, 

 Trans., p. 48, PI. v., fig. 20. Rab. PI. Eur. Alg., sect, i., p. 218. 

 The depression of the valve at the ends is marked by a "well-defijied 

 line "which renders the species easy of identification. 



Ballysodare, Co. Sligo. Lough Gill, Co. Kerry, llalahide, Co. 

 Dublin. 



Navicula hungarica, (Gruno-w). Fresh -water. 



Yalve small, oblong ; elliptical, ends rounded. Striae subdistant, 

 strongly costate, radiate ; central nodule large ; length "0009, breadth. 

 •0045. (Plate 34, fig. 19.) 



Gruno-w, Yerhand. der K. K. Zool. Pot. Gesell., Band x., 1860, 

 p. 539, T. iii., fig. 30. Schumann, Diat. der Hohen Tatra, p. 76. Eab. 

 PI. Eur. Alg., sect, i., p. 190. 



Lough Gill, Co, KeiTy, Ditch near town of Sligo. Lough Mask, 

 near Tourmakeady, Co. Mayo. 



Navicula carassius, (Ehr.) Presh -water. 



Yalves small, broadly elliptical ; ends broadly and shortly pro- 

 duced. Strise costate ; radiate ; length -0007, breadth -0003. (Plate 

 84, fig. 20.) 



Kiitz. Bac, p. 95, T. sxviii., fig. 67. The description and figure 

 represent the valve as unstriate, but the strise are quite obvious. 

 Grunow, Yerhand. der K. K. Zool. Bot. Gesell., Band x., p. 537, 

 T. iii., fig. 31, and T. iv., fig. 11. Ealfs, in Pritch., p. 900. 

 Donkin, N. H. Brit. Diat., p. 20, PI. iii., fig. 7. It is more than 

 doubtful if the form described by Donkin as jS'avicula carassius 

 belongs to this species. The figure represents the form as very much 

 longer, the ends finer and more produced, than is the case in Navicula 

 carassius ; the strife too, are described as granular, the strife in jS'avicula 

 carassius are linear, Donkin regards the species as identical "with 

 Navicula lacustris, Gregory, Q. J. M. S., 1856, p. 6, PI. i., fig. 23b., 

 but the true Navicula carassius is broadly elliptical, and not linear, 

 as the former is represented to be. Schumann, Diat der Hohen 

 Tatra, p. 68. 



Glenchree, Xileool, Co. Wicklo-w. Kileock, Eoyal Canal, Enfield, 

 Co. Kildare. Dundi'um, Co. Dublin. Killeshin, Queen's Co. Caum 

 Lough, near Tralee, Arraglen, Co. Kerry. 



Navicula mutica, (Kiitz.) Eresh or brackish -water. 



Yalve small, broadly elliptical. Striae punctate, radiate ; length 

 •0005, breadth -0003, (Plate 34, fig. 21.) 



Kiitz. Bac, p. 95, T. iii., fig. 32, -who found the form in rain 

 pools mixed -with salt -water, Gruno-w, Yerhand, der K. K. Zool. 



