O’Mrara—Report on the Irish Diatomacee. 385 
Donkin, N. H. Brit. Diat., p. 7, Pl. i. fig. 6. Grunow, Verhand. der 
K. K. Zool. Bot. Gesell., Band x., 1860, p. 531. Heiberg, De Danske 
Diat., p. 81. Cleve, Om Svenska och Norska Diat, p. 226. Schumann, 
Die Diat. der Hohen Tatra., p. 69. Lagerstedt, Sdtvat. Diat. fran 
Spetsbergen och Beeren Eiland, p. 27. Schmidt, Atlas der Diat., T. 
vu. figs. 31, 32.—Navicula ovalis, Wm. Sm., B. D., Vol. 1., p. 48, 
Pl. xvi., fig. 1538a. 
Tacumshane, Co. Wexford. Lower Lake, Killarney, Co. Kerry. 
Glenchree, Powerscourt, Co. Wicklow. Lucan, Killakee, Boherna- 
brena, Co. Dublin. Feighcullen, Royal Canal, near Enfield, Co. Kil- 
dare. Pond, near the city of Armagh. 
Var. costata, (O’Meara). Fresh, or brackish water. 
Valve strongly resembling the typical species, but strie distinctly 
costate, and intermediate free space included between the inner mar- 
gins of the inner striate band lanceolate, but slightly expanded in the 
middle. 
This variety has been found in localities where marine and fresh 
water forms are mixed. 
Breaches near Newcastle, Co. Wicklow. Lough Gill, Co. Kerry. 
Var. davidsonii, (O’Meara). - Fresh water. 
Valve ovate-elliptical. Strize very fine, moniliform ; space included 
within the inner margin of the inner striate band linear, roundly 
expanded in the middle. 
This variety was first brought under my notice by my valued corres- 
pondent, Rey. George Davidson, of Logie, Coldstone, near Aberdeen, | 
who found it in his neighbourhood. It has since been noticed by me 
in various localities in Ireland. On first view this form would seem 
to belong to Navicula estiva, and when first noticed by me in a fresh 
water gathering, I considered it was a stray form of the species men- 
tioned, which had come there by accident ; but subsequent observation 
induced me to give up this view, and to consider the form a well marked 
variety. It is likely the same as that figured by Schmidt in his Atlas 
der Diat., T. vi., fig. 33. 
Moist Rock. Portrush, Co. Antrim, Lough Mask, near Tourma- 
keady, Lough Neagh, near Lurgan, Co. Armagh. 
Var. ovalis, (Wm. Smith). Fresh water. 
Valve linear, oblong, with rounded ends; strize much finer than in 
the case of the typical form; length about -0016, breadth about 
"0005. (Plate 32, fig. 22.) 
Navicula ovalis, Wm. Sm., B. D., Vol.i., p. 48, Pl. xvu., fig. 153 a. 
Under the impression that this form and Navicula elliptica were iden- 
tical, Smith abandoned the specific name of ovalis, and merged the two 
