344 Proceedings of the Royal Irish Academy. 



Navicida trevelyana, (Donkin.) Marine. 



Frustiile on front view deeply constricted, with, trnneate extremi- 

 ties ; middle and end nodules apparent, witli a narrow slightly Innate 

 unstriate band at either side of the central nodule ; Talve linear, rounded 

 at ends ; length about "0048, breadth about "0008 ; median line some- 

 what undulate ; intermediate free space narrow, except around the 

 median nodule, where it is much and roundly expanded; costse strong, 

 converging in the middle, and radiate towards the ends. (Plate 30, 

 fig. 9.) 



Donkin, Q. J. M. S., 1861, p. viii., PI. 1, fig. 2. Do. K H. Brit. 

 Diat., p. 66, PI. 10, fig. 6. — Pinnularia trevelyana, Eab. PI. Eui\ Alg. 

 sect, i., p. 210. 



Eannow, Co. Wexford.* llalahide, Co. Dublin. 



NavicuJa olhnga, (Kiitz.) Presh water. 



Prustules on front view quadrangular, narrow ; valve narrow, 

 elliptical ; length about -0058, breadth about '0007 ; apices broad, 

 rounded ; costte strong, convergent ; intermediate free space narrow, 

 except in middle, wkere it is roundly expanded. (PI. 30, fig. 10.) 



Kiitz. Bac, p. 97, T.iv., fig. 21. Pvalfs, inPritch., p. 907. Gru- 

 now, Yerhand. der K. K., Zool. Bot. Gcscl, Band x., 1860, p. 523. 

 Cleve, Om Svenska och jS'orska Diat., p. 225. — Pinnularia oblonga, 

 "Wm. Sm. B. D., Yol. i., p. 54, PL xviii., fig. 165. The form described 

 by Rabenhorst, Siissw. Diat., p. 45, T. vi., fig. 6, as Pinnularia 

 oblonga, is obviously diiierent from the present species. 



Castlebridge, Co. 'W'^exforcl. Eivcr near Glencar, Co. Kerry. 

 Pond, Ifewcastle-Lyons, Co. Dublin. Powerscourt Demesne, Kilcool, 

 Co. AYicklow. 



Navicula oblonga, var. lanceolata, (Grunow.) Presh. vratcr. 



Yalve shorter and broader than in the typical form, lanceolate, 

 with, rounded ends ; intermediate free space narrow. 



Grunow remarks that this variety " stands near to Pinnularia pere- 

 grina, as described by Wm. Smith," but it is certainly distinct, being 

 found in localities beyond the reach of marine influence. It may 

 be distinguished from Kavicula peregrina by the intermediate free 

 space, expanded in the middle, which, that form does not exhibit. 



Grunow, Yerhand. der K. K. Zool. Bot. Gcscl., Band x., 186G, p. 

 523, T. iv., fig. 25. 



Louth Mourne deposit, Co. Antrim. 



Navicida longa, (Gregory.) Marine. 



Yalves lanceolate; length about -0060; breadth about -0010; 

 costse strong, distant, slightly radiate in the middle, more radiate 



