404 Proceedings of the Royal Irish Academy. 



Navicida incisa, N. S. Marine. 



Yalve deeply constricted ; median compartment narrow ; inflexed 

 at ends, slightly contracted in the middle ; compartments at either 

 side narrow, striate ; striae faint ; marginal band of striae narrow in 

 the middle, wide towards the middle of the lobes ; striae convergent 

 in the middle, nearly parallel for some distance, and slightly radiate 

 towards the ends ; costate, divided into four distinct equal bands, by 

 three deep sulci, which lie conformably with the outer margin ; the 

 costae in each band appear slightly curved ; length -0035, breadth 

 •0015 ; breadth at the constriction -0010. (Plate 33, fig. 33.) 



This form somewhat resembles that figured by Schmidt, Atlas der 

 Diat., T. sii., figs. 21 to 24, without a name, and which he thinks 

 stands between Navicula apis and jS'avicula splendida, but I doubt 

 its identity with either. 



Arran Islands, Co. Galway. 



Navicula cralro, (Ehr.) Marine. 



Yalves large, slightly constricted ; median compartment narrow, 

 slightly inflexed at ends, constricted in the middle ; compartments on 

 either side wider, gently tapering towards the ends ; striate, the ends 

 of the striffi appearing as large puncta on the elevated margin of the 

 inner edge ; marginal striate band wide ; striae convergent in the 

 middle, radiate towards the ends ; costate; length "OOTS, breadth 

 •0021 ; breadth at constriction "0015. 



AYm. Sm., B. D., Vol. ii., p. 94. Donkin, Is". H. Brit. Diat., 

 p. 46, PL vii., fig. la. Ealfs, in Pritch., p. 894. Eab. PI. Eur. Alg., 

 sect, i., p. 204. — Diploneis crabro, Ehr., Mic, T. xix., fig. 29. 

 — I^avicula pandura, De Brebisson, Diat. du Littoral de Cherbourg, 

 p. 16, PL i., fig. 4. — Pinnularia pandura, var. elongata, Gregory, Diat. 

 of Clyde, p. 489, PL ix., fig. 22. Though Ealfs and Eabenhorst seem 

 to regard this form as distinct from jSTavicula pandura, I am inclined 

 to think with Donkin, that there is no distinction between them. 

 Smith describes the striae as obscurely monilif orm ; but all the figures I 

 have seen represent the striae as distinctly costate, and such I consider 

 is their normal character. Donkin' s figure represents the compart- 

 ments at either side of the median compartment as unstriate, except 

 on the inner edge, where there is a row of large bead-like detached 

 puncta. In all the specimens I have seen, the costae in this portion, 

 though of a fainter colour, are clearly traceable all through ; the 

 large puncta described by Donkin being simply the ends standing out 

 distinctly on an elevated ridge. 



Arran Islands ; Stomachs of Ascidians, Eoundstone Bay, Cc. 

 Galway. 



