384 Proceedings of the Royal Irish Academy. 
Var. rhombiea, (O’Meara). Marine. 
Valve like that of the typical form in general structure, but dif- 
fering in its distinctly rhombic outline, as well as in the rhombic form 
of the inner band of strie. 
A form which seems to me to be identical with this is described by 
Schmidt, Atlas der Diat., T. vu, fig. 18. 
Arran Islands, Co. Galway. 
Navicula collisiana, N. 8. Marine. 
Valve broadly elliptical. Nearly linear at the margin, with broadly 
rounded ends. Intermediate space wide, oblong, elliptical. Strice cos- 
tate. Marginal striate band wide, striz distinctly moniliform, nearly 
parallel in the middle; more and more radiate towards the ends; 
length :0026, breadth :0016. (Plate 32, fig. 19.) 
This form is distinguished from Navicula fusca, and Navicula 
smithu, which in other respects it strongly resembles, by the broad 
oblong elliptical outline of the inner striate band, and more specially 
by the fact that the striz in this portion of the valve are distinctly 
costate, while in the others they are moniliform. It was first ex- 
hibited by me at a meeting of the Dublin Microscopical Club, some: 
years since, at the house of the late Surgeon Maurice Collis. 
Stomachs of Ascidians, Roundstone Bay, Arran Islands, Co. 
Galway. Kailcool, Co. Wicklow. 
Navicula estiva, (Donkin). Marine. 
Valve linear, elliptical ; strize fine, obscurely moniliform, parallel i 
the middle, slightly radiate towards the ends; inner striate band narrow, 
elliptical ; length about -0022; breadth about -0010. The distinctive 
character of this species is the fineness of the strie. (Plate 32, fig. 20.) 
Donkin, Q:.JM. °S, ‘Prans., 1858, p- 32, (Pl. mig fie, I; tand 
N.H. Brit. Diat., p. 6, Pl.i., fig.3. Donkin’s figures represent the spe-- 
cies as much larger than my specimens would lead me to regard it. 
Ralts, in Pritch., p. 899. Rab. Fl. Hur. Alg:, sect. 1., p. 184. 
Arran Islands, Stomachs of Ascidians, Broadhaven Bay, Co. Gal- 
way. 
Nawvicula elliptica, (Kiitz.) Fresh water. 
Valve elliptical; strie of the marginal band distinctly moniliform, 
converging in the middle, radiate towards the ends; inner striate band 
very narrow; free space about the median line greatly expanded, 
forming a rounded rhombic outline ; median line strongly developed ; 
length about :0020, breadth about ‘0011. (Plate 32, fig. 21.) 
Kiitz. Bac., -p: 98,’ T.: xxx.,; fig. 56. Wm Sms Be Di; Welkei.,. 
p. 92. Ralfs, in Pritch., p.899. Rab. Fl. Eur. Alg., sect. 1.,p. E792 
