386 Proceedings of the Royal Irish Academy. 
forms under the one designation Navicula elliptica. However close 
the resemblance must be acknowledged to be, there is such a difference 
in the details of structure as to require notice. Ralfs, in Pritch., 
p. 899, regards the form as identical with Navicula elliptica, and the 
same view is adopted by the following authors: Cleve, Om Svenska 
och Norska Diat., p.226. Rabenhorst, Fl. Eur. Alg., sect. i., p. 179. 
Donkin, N. H. Brit. Diat. Lagerstedt, Sotvat. Diat. frin Spetsbergen 
och Beeren Eiland, p. 27, and probably Grunow, Verhand. der K. K. 
Zool. Bot. Gesell., Band x., 1860, p.531. Castracane includes the two 
forms under the designation of Navicula ovalis; Catalogo di Diat. rac- 
colte nella Val. Intrasca, p. 12. Schmidt, treating the two forms 
as distinct species, describes the present as Navicula ovalis; Atlas der 
Diat. T. vi., figs. 34 and 35. 
Camolin, Co. Wexford. Lough Neagh, near Lurgan, Co. Armagh. 
Lough Gill, Co. Kerry. Lough Mourne deposit. 
Var. parva, (O'Meara). Fresh water. 
Valve like the last variety, but very much smaller, and the stria- 
tion extremely indistinct ; length -0008, breadth 0004. 
It seems not improbable that this variety is identical with that de- 
scribed as Navicula oblongella by Schmidt, Atlas der Diat., T. vii., 
fig. 53. 
Camolin, Co. Wexford. 
(1) Clavate. 
Valves elliptical; strie in two distinct bands, one marginal, another 
close to the median line, with a wide elliptical intervening space. Mar- 
ginal band of strie@ lunate on the inner margin. 
Navicula clavata, (Gregory). Marine. 
Valve broadly elliptical; ends broadly produced and rounded; 
strie moniliform, marginal band broad, narrowing towards the ends; 
inner bands of strie separated from the median line by a narrow 
unstriate space, bending outward near the central nodule, where they 
terminate sharply, making a wide free space about the central nodule ; 
space intervening between the inner and outer bands of strize un- 
striate, broad and lunate; length about °0050, breadth about -0026. 
(Plate 32, fig. 23.) 
Gregory, Q. J. M. S.. Trans. 1856, p. 46,*Pl.-v., fig. 17. Ralfs, 
in Pritch., p. 898. Donkin, N. H. Brit. Diat., p. 15, Pl. u1., fig. 8.— 
Navicula lyra, Rab. Fl. Eur. Alg., sect. i., p. 178. 
Stomachs of Ascidians, Co. Clare. Stomachs of Ascidians, Round- 
stone Bay; stomachs of Ascidians, Broadhaven Bay, Arran Islands, 
Co. Galway. 
