O’Mrara—Report on the Irish Diatomacee. 295 
Rhaphoneis amphiceros, (Ehr.) Marine. 
On side view valves short, broadly rhomboid; very slightly pro- 
duced at the apices; striz large, moniliform, radiate; median free space 
linear, and very narrow, so much s0 as to be sometimes scarcely dis- 
cernible ; frustules stipitate. (Pl. 28, fig. 3.) 
Ralis. in’ Prtch., p.-791, Pl. xiv., fig. 21.. Rab. FI. Eur., sect. 1, 
p. 126.—Doryphora amphiceros, Kiitz. Bac., p. 74., T. xxi., fig. 2. 
Wm. Sm., B. D., Vol. i., Pl. xxiv., fig. 224. Grunow, Verhand der 
K. K. Zool. Bot. Gesel., Band xii., 1862, p. 384. 
From mud on sea-shore, Co. Clare, supplied by Professor Sullivan. 
On Sea-weeds, Co. Clare. On Sea-weeds, Co. Donegal. 
Var. leptoceros, (Ehr.) Marine. 
Similar in all respects to Rhaphoneis amphiceros, but longer, nar- 
rower, and the ends produced into long beaks. 
Rhaphoneis leptoceros, Ralfs, in Pritch., p. 791. 
Sea-weeds, Co. Donegal; sea-weeds, Co. Clare. 
Rhaphoneis rhombus, (Ehr.) Marine. 
Valves narrow, elliptical; ends rounded, strie fine; moniliform ; 
parallel in the middle, and slightly radiate towards the ends; median 
unstriate space narrow, linear in the middle, and expanding towards 
the ends. 
Ralfs, in Pritch, p. 792. Grunow, Verhand der K.K. Zool. Bot. 
Gesel-. Band *xi.,’ 1862; ps 37/9, Ti iy., tig. '36. Roper, Q. 32 M_S., 
Trans., Vol. u1., 1854, Pl. vi., figs. 7-10. 
Concerning this form, Grunow, as above cited, makes the following 
noteworthy remarks :—‘‘ Rhaphoneis rhombus ought to be considered 
as the type of the genus Rhaphoneis, which must ever stand, though 
other species be separated as not belonging toit. The frustules in 
contradistinction to Doryphora occur free, as I consider I have satisfied 
myself to be the case.” 
Sea-weeds, Dundalk, Co. Louth. Piles of the wooden bridge, 
Dollymount, Co. Dublin. Sea- weeds, Co. Donegal. 
A smaller variety occurs frequently in the last named gathering, 
much broader for the length than the ordinary specimens, but in other 
respects so similar that it cannot be considered even a variety. 
Rhaphoneis scutelloides, (Grunow.) Marine. 
Valves small, on front view broadly elliptical, rounded at the ends, 
stire obscurely moniliform, nearly parallel at the middle, and slightly 
radiate towards the ends; median free space, narrow, elliptical. (Pl. 
28, fig. 4. 
ee Verhand der K.K. Zool. Bot. Gesel., Band xii., 1862, p. 
383, T. iv., fig. 34. 
Sea-weeds, Co. Donegal. 
