O’Mrara—Report on the Irish Diatomacee. 327 
Mastogloia apiculata, (Wm. Sm.) Marine. 
Valves broadly elliptical; shghtly produced at the ends; median 
line fine, with two sulci, one at either side, and very close to it; 
parallel for greater part of length, and converging towards the ends; 
central nodule small; marginal plates narrow, gradually attenuated 
towards the ends, where they suddenly decrease in breadth; loculi 
numerous; space between the inner margins broadly elliptical, and 
slightly expanded at the ends; strie fine, closely punctate, slightly 
radiate. 
Wm. Sm0./B..D. Vol.-ii., p:65., Supp. Pl..1xu., fig. 387., Ralts, 
in Pritch., p. 925. Grunow, Verhand. der K.K. Zool. Bot. Gesel., 
Band x., 1860, p. 577, 1. vii., fig..9. Rab. Fl. Eur., sect. 1, p. 262. 
Dollymount Strand, Co. Dublin. Stomachs of Ascidians, Round- 
stone Bay, Co. Galway. 
Mastogloia smithii, (Thwaites.) Fresh or brackish water. 
Valves elliptical ; frequently produced at the ends ; marginal plates 
relatively broad; attenuated at the ends; space included between the 
inner margins narrow; slightly expanded at the ends; strix fine, 
linear; slightly radiate. (Pl. 29, fig. 12.) 
This form varies greatly in size‘and shape, as well as in the habitat. 
It seems essentially a fresh water form, for I have found it frequently 
in localities far remote from marine influences; and also in places 
where, so far as I could judge, there was no likelihood of mixture of 
fresh water with the salt. Under the circumstances, I was anxious 
to submit the forms to the most rigid examination, but could detect 
no specific difference between them. Grunow observes that, in the 
specimen that came under his notice, there was even a tolerably wide 
transversely expanded central nodule, which he considers should be 
established as the characteristic distinction between this species and 
Mastogloia lanceolata. I may mention that this feature, though 
frequently noticeable, is not of universal occurrence. 
Wm. Sm., B.D., Vol. i., p. 65, Pl. liv., fig. 341. Ralfs, in Pritch., 
p-. 925. Grunow, Verhand. der K. K. Zool. Bot. Gesel., Band x., 1860, 
p. 575, T. vig fig. 11. Rab. Fl. Eur:, sect..1, p..261.) Cleve, Om 
Svenska och Norska Diat., p. 230. 
Tacumshane, Co. Wexford. Lough Gill, Co. Kerry. Kilcool, 
Co. Wicklow. Newtownlmavady, Co. Derry. In all which gatherings 
there was a mixture of fresh and brackish forms. Tide pool, Greystones, 
Co. Wicklow, where the forms were mostly marine. Lough Corrib, 
Co. Galway, wholly free from marine influence. 
Var. capitata, (Wm. Sm.) Fresh water. 
Agreeing with the typical form, only that the produced ends are 
capitate; the strize, also, which are similarly arranged, may easily be 
resolved into minute dots. 
Wm. Sm.,.B.D., Vol. m., p..65, Pl. liv., fig. 341 8. “In allpro- 
