320 Proceedings of the Royal Irish Academy. 
Striatella unipunctata, (Lyng.) Marine. 
Diagnosis same as that of the genus. (PI. 29, fig. 6.) 
Kutz. Bac., p. 125, T. xviu., fig. 5, who considers the form 
identical with Fragilaria unipunctata, Lyngbye. Wm. Sm., B. D., 
Vol. u., p. 36, Pl. xxxix., fic. 307. (Ralis, im Pinteh 7p. 803; 0lav 
fig.40. Grunow, Verhand. der K.K. Zool. Bot. Gesel., Band xi1., 1862, 
p. 427. Heiberg, De Danske Diat., p. 72. Rab. Fl. Eur., sect. 1, 
p- 807. Cleve, Om Svenska och Norska Diat., p. 222. 
Sea-weeds, Bray, Howth, Salt Hill, Co. Dublin. Stomachs of 
Ascidians, Co. Clare. Sea-weeds, Co. Galway. ‘‘ Larne and Belfast 
Bays, Cork Harbour,” Wm. Smith. 
Genus VI. TerssEtia, Ehr. 
Frustules stipitate, stipes short; not filamentous; diaphragms 
apparently reaching not further than the middle of the valve, alter- 
nate, arched, and in opposite directions on the opposite sides of the 
frustule; external edges of the diaphragms slightly striate. 
Tessella interrupta, (Ehr.) Marine. 
Diagnosis of the species same as that of the genus. Of the side 
view of this species, I have never been able to obtain a satisfactory 
observation. (Pl. 29, fig. 7.) 
Kiitz. Bac., p. 125, T. xviii., figs. 41, 2. This author states with 
hesitation that there is no stipes in this species, as also does Ralfs, in 
Pritch., p. 804, Pl. vii., fig. 5—Striatella interrupta, Grunow, Ver- 
hand. der K. K. Zool. Bot. Gesel., Band xii., 1862, p.427. It is tobe 
noticed that this species cannot be confounded with Striatella inter- 
rupta, as described and figured by Heiberg, De Danske Diat., p. 75, 
i y., oe: 15, and Rab. Et “Mur sect. p. old: 
Sea-weeds, Co. Galway. Sea-weeds, Co. Clare; in both which 
localities it occurs in company with Striatella unipunctata. 
Famity VII. AMPHIPLEUREA, Kiitz. 
Frustules free; lanceolate on side view; with median line and long 
narrow end nodules, but without central nodule, and exhibiting a sub- 
marginal keel at each side. 
Genus I. AmpuriprEevra, Kiitz. 
The characters of this genus may be regarded as those of the 
family. It will be found that the structure of the frustules in 
