136 Proceedings of the Royal Irish Academy. 



in the basal cylinder and under the head ; while others again do not 

 show any medial swelling. Lomas regards these latter as imperfectly 

 developed forms. 



I have also found it in considerable quantity on algse, obtained by 

 the Eoyal Dublia Society Suiwey from Killybegs, and from Smei-wick 

 Harbour. 



Habitat. — On sea- weeds, from shallow water. 



Localities. — Isle of 3Ian (Lomas) : Killiney, Dublin Bay (J. E. 

 Duerden) : Killybegs and Smerwick Harbour (Roy. Dub. Soc). 



explajs^atiois" oe plate Y. 



EiG. 1. Triticella Tcorenii, Sars, with a portion of base, llagnified. 



EiG. 2. TriticeUa hoecTcii, Sars. Magnified. 



Ei&. 3. Triticella pedicellata, Alder. Magnified. 



Fig. 4. Barentsia nodosa, Lomas. ^Magnified. 



Fig. 5. Two connected patches of horny crust of T. pedicellata, 

 Alder, llore highly magnified. 



Fig. 6. Irregular homy crust of T. loechii, G. 0. Sars, with 

 sis peduncles arising from it. More highly magnified. 



