O’Mreara—Report on the Irish Diatomacee. 325 
attenuated towards the ends; strie linear, fine; slightly radiate; not 
quite reaching the median line, but terminated by two strongly 
developed sulci, which bend in slightly towards the central nodule at 
either end, leaving a narrow lanceolate space about the median line 
free from striz. 
Smith and Grunow, the former doubtfully, regard this form as 
identical with Navicula meleagris, Kiitz. Bac., p. 92, T. xxx., fig. 37. 
Rabenhorst, however, regards Kiitzing’s form as distinct from the 
present ; and in this I am disposed to agree with him, as I have seen 
specimens exactly corresponding with that of Kiitzing, and as I think 
quite distinct from Mastogloia lanceolata. 
Wm. Sm., B. D., Vol. ii., p. 64, Pl. liv., fig. 340. The figure 
and description are correct, as far as they go, but neither the longi- 
tudinal sulci about the median line, nor the stria are described. 
Ralfs, in Pritch., p. 924. Grunow, Verhand. der Zool. Bot. Gesel., 
Band x. 1860, p. 576. Heiberg, De Danske Diat., p. 94. Rab. FI. 
Kur., sect. 1, p. 261. Cleve, Om Svenska och Norska Diat., p. 230. 
Tacumshane, Co. Wexford. Lough Gill, Co. Kerry. Salt marsh, 
Kilcool, Co. Wicklow. Salt marsh near the town of Galway. Dolly- 
mount Strand, Co. Dublin. a 
Mastogloia convergens, N.S. Marine or brackish water. 
Valve broadly elliptical; length -0018; breadth -0008; rounded 
at ends; median line straight, strongly marked, and of equal breadth 
throughout; central nodule small and round: marginal plates broad 
in the middle, gradually attenuated towards the ends, at some dis- 
tance from which they bend outwards; the space between the plates 
is broadly lanceolate at either end, and narrower in the middle, where 
the boundary line curves very gently towards the margin; loculi 
broader than in the last; striz fine, linear, convergent in the middle 
of the valve, where they are stronger and farther apart, and for the 
remainder gently radiate. (Pl. 29, fig. 9.) 
On first view, this form might readily be confounded with the 
preceding ; but the more carefully it is examined, the more apparent 
are its distinctive characteristics. In its outline, it is broader for the 
length than Mastogloia lanceolata; its ends are broader, and more 
round. In the latter, the loculi are more numerous, shorter ‘in the 
middle, and gradually diminishing towards the ends; in the present 
case, the loculi are wider in the middle, and suddenly become attenu- 
ated towards the ends. The longitudinal sulci near the median line, 
so marked a feature of M. lanceolata, are wanting in this. In M. 
lanceolata, the striz are uniformly radiate; in M. convergens, they 
are convergent in the middle, and for the rest more decidedly radiate 
than in the other. 
Salt marsh near the town of Galway. Lough Gill, Co. Kerry, 
accessible to the tide. 
