15 140 Proceedings of the Royal Irish Academy. 



of a dark cave-pool during the last day spent on the island ; owing to it- 

 minute si/e, it was difficult to secure, the plants on detachment being easily 

 lost in the water. No tetrasporic or cystocarpic plants were obtained, but 

 sufficient material was collected to show general characters. The plant 

 is closely allied to P. micrqpterwm, which was described by Montague from 

 the Canary Islands. Sauvageau also collected it on Cystoseira at Guethary. 

 and in recording the same, adopted a suggestion by Bornet, and removed 

 the plant from Oallithamnion to Ptilothamnion (Sauv., '07, p. 206). Monsieur 

 Hariot kindly allowed me to examine the Canary Islands type from the 

 Paris Museum; and it was found to consist of a smaller and much more 

 compact plant, probably of epiphytic habit. The Guethary specimens appear 

 to have been mislaid. Beinsch'a C. pinastroides (suggested as a synonym in 

 Dc Toni, Syll. Alg., iv) is certainly distinct; but Hauck's C. pluma from 

 Trieste (Beitrage, vii, 1878, p. 131) proves, on examination of the specimens 

 kiudly lent me by Madame Weber, to be P. micropteron. Xo other record 

 exists. As P. micropteron is so very little known, it is within the bounds 

 of possibility that the Irish plant is an extreme form of that alga ; but 

 taking all things into consideration, it appears wiser to regard it as a 

 distinct species. 



Spermothamnion Turneri var. subverticillatum comb. nov. 



Oallithamnion Turneri var. subvert icillatum, Lenorm. MS., in Herb. 

 C. subverticillatum, Zanard. in Kutz. Tab. Phyc, xi, tab. 81 ? 



The specimens referred to this variety agree precisely with plants so 

 named by Lenormand in the Kew Herbarium. C. subverticillatum Zanard. 

 is most probably the same plant, but apparently Zanardini's specimens 

 were not kept, as the plant is not listed in DeToni's catalogue of his 

 herbarium. The variety differs from the ordinary form in the elongated 

 slender shoots, and in the sub-verticillate branching. In Clew Bay it 

 was found on several occasions, but always in a floating condition. As 

 seen thus it is very distinct, and would appear to be a good species, as 

 Zanardini believed ; but whether the characteristic habit is due merely to 

 growth subsequent to, and resulting from, detachment was not ascertained. 

 Until this can be determined, and the question of Zanardini's plant inquired 

 into, it appears best to regard the alga as a variety. 



Griffithsia corallina Ag. 



Occurs in the greatest profusion during spring in Clew Bay and Achill 

 Sound. It is largely epiphytic and is found in channels and in shallow water. 



