15 136 Proceedings of the Royal Irish Academy. 



tetrasporic sori are not infrequent, being produced in special short branches. 

 The plant is very closely allied to N. reptans Cm. ; and it is doubtful whether 

 they are really distinct. I have not had the opportunity of examining a good 

 series of the latter plant. For an account of the anatomy and physiology of 

 algae with uncinate branches see Nordhausen ('99). 



To sum up, the deep colour, lack of iridescence, and acuminate branches 

 clearly mark this species, whilst its sub-littoral habit and obviously terminal 

 hooks also aid in separating it frorn the uncinate form of X. laceration. It is, 

 however, allied to that species ; and they have this feature in common, that 

 they are both liable to be infected with the parasite Gonimophyllum. 



Bonnemaisonia hamifera Hariot. 



The discovery of Bonnanaisonio hamifera on the west of Ireland raises 

 doubts as to whether this alga is not after all indigenous to Europe. Originally 

 described from Japan, it has been usually regarded as a plant introduced to 

 the south coast of England. It was collected by T. H. Buffham at 

 Falmouth in 1895, and was subsequently found at Torquay and Shanklin 

 (Isle of Wight). The Rev. H. Boyden tells me he has gathered it within the 

 last few years at several widely separated localities in Cornwall (West 

 Looe, Falmouth, and Penzance^ ; and I have noted it for some five or six 

 seasons in rock-pools at Weymouth. Chalon lists it from Cherbourg on the 

 other side of the Channel, but it is not known elsewhere in Europe. It is 

 locally frequent, but never abundant. 



With regard to Clare Island it was with some astonishment that several 

 fronds of the plant were emptied out of a tube of mixed algae collected at 

 Kinnacorra in June. 1910. In October of the same year, and in April of the 

 next, the locality was specially searched, but no further specimens were found. 

 During August, 1911, however, one or more loose fronds were noted in Achill 

 Sound, Roonah Point, and Clare Island, so that there is no doubt whatever 

 that the species occurs in the district (see p. 16" ). 



Laurencia hybrida Lenorm. 



Although our three British species of Laurencia are perfectly distinct, 

 considerable confusion exists with regard to the present species, which is 

 usually found in herbaria, not only under the names of L. hybrida and 

 L. caespitom, but also on the same sheets as L. pinnatifida and L. obtusa. The 

 plant is poorly described in most of our floras, and the confusion is increased 

 by a. difficulty as to names. 



Nomenclature. — The name to be used is clearly L. hybrida (DC.) Lenorm. 

 Fucus hybridus was described by De Candolle in 1805 ("Flore Francaise,"' ii, 



