O'Meara — Report on the Irish Diatomacece. 249 



Bac, p. 52, T. iii., fig. 3. Wm. Sm., B. D., Vol. ii., p. 55. PI. xlix., 

 fig. 329. Ealfs, in Pritch., p. 816, PI. v., fig. 64 and PI. xi., fig. 14. 

 There is considerable difference of opinion as to the founder of this 

 species ; Smith assigns it to Kiitzing, Palf s to Dillwyn and Agardh. 

 On this subject Heiberg says, "As above mentioned, 0. P. MuUer 

 was probably the first to discover this species, and describe it under 

 the name of Conferva moniliformis, or strand-necklace, but that can- 

 not be ascertained "with certainty. The present specific name is 

 attributable to Dillwyn, who in 1809 described a Conferva nummu- 

 loides, which Lyngbye cites as a synonym under his Pragillaria num- 

 muloides. But as meanwhile there do not appear to be any original 

 specimens of Dillwyn' s species, and his figures can only be approxi- 

 mately identified, while the numerous specimens of Lyngbye which 

 still exist are all attributable to our species, it seems most proper to 

 name Lyngbye as the author." De Danske Diat., p. 29. 



Brackish ditch near Wexford, ITalahide, Dollymount, IS'orth- 

 wall, Co. Dublin. Salt ditch near "Wicklow, and many other places 

 too numerous to mention. 



Lysigonium Westii, (Wm. Sm.) Marine. 



Prustules somewhat conical, furnished with two keels, one at the 

 suture, another near the end, considerably thicker than the similar 

 structure in Lys. nummuloides, and not projecting upwards to the 

 same extent. 



Melosira Westii, Wm. Sm., B. D., Yol. ii., p. 59, PI. Hi., fig. 333. 

 Ealfs, in Pritch., p. 817. Bab. PL Eur., p. 38. 



Dollymount, Oyster beds, Howth, Co. Dublin. !N"ear "Wicklow. 

 Stomachs of Ascidians, Boundstone Bay, Co. Galway. 



Lysigonium Wrightii, (O'Meara.) Marine. 



Prustules rounded at the ends, narrow, surrounded by a broad 

 keel, which curving slightly outwards and upwards, then bending in- 

 wards and downwards to the surface of the valve, forms round it a 

 crown-like rim. In the front view two nodules are observable in the 

 central portion of the valve ; the frustule is perfectly hyaline, without 

 sculpture of any kind. 



O'Meara, Q. J. M. S., Vol. ix., PI. xii., fig. 3. 



Arran Islands, Co. Galway. 



Genus III. Podosera, Ehr. 



Pilaments attached by a distinct stipes, and generally short, con- 

 sisting of a few frustules. 



Heiberg regards the character on which this genus is founded as 



