252 Proceedings of the Royal Irish Acadetny. 



Besides the localities specified by Smith, namely, near Belfast 

 and Lough Mourne deposit, I have found the species in the following 

 places : — River Erne, Crossdoney, Co. Cavan ; ditch near Wexford ; 

 verner's-bridge, Co. Armagh; Killakee, Co. Dublin; stream near Kil- 

 cool, Co. Wicklow ; L. Neagh, near the town of Antrim ; surface of 

 rock near Glenarm, Co. Antrim. 



Orthosira sulcata, (Ehr. Kiitz.) Marine. 



Spines of junction surfaces large, short, and more distant than in 

 the former species. Striae on side view linear, radiate, distinct at the 

 margin, attenuated towards the centre, which they do not reach; 

 puncta at the suture large ; striae on front view linear, direct, parallel 

 (PI. 26, fig. 7.) 



Melosira sulcata, Kiitz. Bac, p. 55, T. ii., fig. 57. Balfs, in 

 Pritch., p. 819; PI. ix., fig. 131; Plate xi., fig. 26. Rab. El. Eur. 

 p. 41. — Orthosira marina, "Wm. Sm., B. D., Vol. ii., p. 59; PI. liii., 

 fig. 338. — Gallionella sulcata, Ehr. — Paralia marina, Heiberg, De 

 Danske Diat., p. 33. 



Although this species has been described and figured by Kiitzing 

 as identical with Gallionella sulcata of Ehrenberg, Heiberg attributes 

 it to Wm. Smith. The latter indeed has figured it more perfectly 

 than Kiitzing has done ; still, Kiitzing' s figure, imperfect as it is, 

 seems to me unmistakable ; and all uncertainty as to the species indi- 

 cated is removed by his reference to the Richmond deposit in which 

 the form abounds. Eor this reason I have followed Ralf s and Raben- 

 horst in assigning the species to Ehrenberg and Kiitzing, as well as 

 restoring the original specific designation. And as I have not been 

 able to trace any keel similar in structure and position to that of Lysi- 

 gonium, instead of adopting Heiberg' s new genus, Paralia, I leave the 

 species where Smith placed it in the present genus. 



Cork and Kinsale Harbours, Wm. Smith. Bannow, River Slaney, 

 Killurin, Co. Wexford. Near Wicklow. Malahide. Dalkey, Co. 

 Dublin. 



Orthosira DicMeii, (Thwaites.) Fresh water. 



Cell-cavity eub-spherical. Sutural puncta small and distant. 

 Spines on junction surfaces absent. Striaj, both on front and side 

 view, minutely punctate. Puncta on front view ai'ranged in lines 

 parallel to the suture. 



Thwaites, Ann. N. H., 2 series, Vol. i., p. 168, PI. xii. Wm. Sm., 

 B.D., Vol. ii.,p. 60, PL lii., fig. 335.— Melosii-a Dickieii, Kiitz. Sp. Alg., 

 p. 889. Ralfs, in Pritch., p. 820, PL xv., fig. 29. Rab. El. Eui\, 

 p. 43. 



This species is remarkable for the abnormal growth of frustule 

 within frustule, so fully described by Smith, B. D., Vol. ii., PL lii., 

 fig. 335. Thwaites regarded this peculiarity as a mode of developing 

 sporangia, while Smith considered it an abnormal development siroilar 



