312 Froceedings of the Royal Irish Academy. 



Eostrevor and Dundruin Bay, Co. Do^^m. Breaclies near T^ewcastle, 

 Co. "Wicklow. Mouth, of the I^annywater, Laytovm, Co. Meath. 



Synedra nif%scTiiocles, (Grun.) ATarine. 



rrastules on front yiew slightly attenuated towards the ends ; on 

 side view narrow, linear lanceolate. (PI. 28, fig. 39.) 



Grunow does not descrihe the mode of growth, nor can I say any- 

 thing on this subject, as the form has been observed by me only after 

 treatment with acid. This species may be distinguished from the last 

 by the linear and slightly apiculate form of the side Yiew. 



Gnmow, Yerhand. der K. K. Zool. Bot. Gesel., Band xii., p. 403, 

 T. v., fig. 18. This species was found by Grrmow only in the Pacific 

 Ocean. 



Prom stomachs of Aseidians, Eoundstone Bay, Co. Galway. From 

 seaweeds, Bush, Co. Dublin, where it occurs in tolerable abundance. 



Synedra fraimifeldii, (Grun.) Marine. 



Prustules much larger than the three preceding species on fi'ont 

 ■dew, but very slightly attenuated at the encls ; on front riew narrow, 

 lanceolate, much attenuated from the middle towards the ends, which 

 are slightly dilated ; striae fine, marginal in the middle, but as the 

 Talyes become narrow towards the ends, thev seem to meet. (PL 28, 

 fig. 40.) 



Grunow, Yerhand. der K. K. Zool. Bot. Gesel., Band xii., 1862, p. 

 406, T. iv., fig. 26. The only habitat given by Grunow is the Ked Sea. 



Seaweeds, Dundalk, Co. Louth. The form is more slender than 

 that figured by Grunow as above, the apex less dilated, and the strise 

 shorter ; but in the main f eatui-es the foiTas are so like as to leave 

 but little doubt of their identity. 



Synedra putealis, IS. ^. Freshwater. 



Frustules in length '0045, veiy naiTOw ; on front view slightly 

 attenuated towards the ends ; on side view narrow, lanceolate, gra- 

 dually tapering towards the rostrate ends ; strife short ; stipes short ; 

 on which the fmstules are crowded in small tablets containing about 

 ten in each. (PI. 28, fig. 41.) 



This form possibly may be identical with that described as Synedra 

 tenuis, by Kiitzing, Bac, p. 65, T. xiv., fig. 10, but in some respects 

 it is so different as to warrant the conclusion that it is specifically 

 distiact. Kiitzing does not describe the mode of growth nor the 

 character of the strise, and moreover alleges that in the species re- 

 ferred to, the frustules are exactly linear on front view, whereas in 

 the present case they are obviously attenuated. 



St. Fenton's Well, Sutton, Co. Dublin. "Well near the Eoman 

 Catholic Chapel, Ballinasloe, in both which localities it occurs in 

 great abundance, mixed with other forms. 



