■262 Proceedings of the Royal Irish Academy, 



Coscinodiscus radiatus, (Ehr.) Maiine. 



Cellules large, hexagonal, radiate, somewliat smaller near tlie 

 margin. 



Ehr. Mic, T. xx., fig. 1. Kiitz. Bac, p. 132, T. i., fig. 18. 

 Wm. Sm., B. D., Yol. i., p. 23, PI. iii., fig. 37. Ealfs, in Pritch., 

 p. 830, PI. xi., figs. 39 and 40. Heiberg, De Danske Diat., p. 36. 

 Cleve, Om Svenska och j^orskaDiat., p. 218. Eab. El. Eur., p. 34. 



On sea-weeds, Bannow, County Wexford. Piles of wooden bridge, 

 Dollymount ; Malahide. Stomach of Pectens, Dalkey. On corallines, 

 Howth. On sea weeds, Ballybrack, County Dublin. On sea weeds, 

 Knkee, County Clare. Erom stomachs of Ascidians, coast of County 

 €lare. 



Coscinodiscus radiolatus, (^Ehr.) ^Marine. 



Disk small, cellules minute, obscurely hexagonal, arranged partly 

 in radiate bands, and partly in the intervals of these bands in converg- 

 ing lines. Cellules confused at the centre of the disk, smaller towards 

 the margin. (PI. 26, fig. 22.) 



Kiitz. Bac, p. 132, T. xxix., fig. 91. Ealfs, in Pritch., p. 830, who 

 describes the form thus : — " Cellules punctiform, equal, radiating," 

 whereas, in fact, they are minutely hexagonal, and diminish slightly 

 near the margin. 



Oyster shells, Dublin Bay. Tide-pool,^ Dalkey, County Dublin. 

 Stomachs of Ascidians, Boiindstone Bay, County Galway. Stomachs of 

 Ascidians, County Clare. 



Coscinodiscus cervinus, (Brightwell.) Marine. 



Cellides very minute, radiate, close, diy valve fawn-coloured, frus- 

 tule convex. 



Brightwell has described and figured this form as Hyalodisciis cer- 

 vinus, Q,. J. M. S., Vol. \aii., p. 95, PI. vi., fig. 13. He describes the 

 ^' puncta or dots " as " scattered over the whole surface ;" but in his 

 figure represents them as regiilarly radiate, which latter corresponds 

 exactly with my specimens. Ealfs, in Pritch., p. 831, places the form 

 among the doubtful species of Coscinodiscus, to which genus it pro- 

 perly belongs. 



Erom stomachs of Ascidians, Eoundstone Bay, County Galway. 

 Erom stomachs of Ascidians, County Clare. 



Coscinodiscus Smithii, (Wm. Sm.) Eresh water. 



Disk small, punctate, puncta regularly radiate. 



"Wm. Sm., B. D.,yol. i., p. 23, PL iii., fig. 36. _ 



Smith has unaccountably confounded this form with Coscinodiscus 

 minor, Ehr., from which it is plainly distinguished, both by its habitat 

 and the character of the striation ; the latter being marine and areolate, 

 the former a fresh water species, and punctate. 



