Clare Island Survey — Marine Algae. 15 121 



Myrionema saxicolum Kuck. 

 Some very beautiful specimens of this rare plant were found on limpet- 

 shells on Clare Island in October, 1910. The sporangia and filaments were 

 slightly larger than in the Heligoland material, but Dr. Kuckuck tells me it 

 is undoubtedly the same species. 



M. reptans Fosl. 

 (= Ectoearpus reptans Crouan ; Ascocyclus reptans Reinke ; Phycocelis reptans 

 Kjellm.; Chilionema reptans Sauv. ; Hecatonema reptans Sauv.; Hecatonema 

 fucicola, Kylin). 



Though no one has thrown more light on the Myrionemaeeae than 

 Professor Sauvageau, a few alterations with regard to his " Memoire " have 

 been found necessary. The present plant proves to be a Myrionema, and not 

 a Chilionema ; hence Foslie's name is restored. It is frequent in the south 

 of England on Fucus spp., but is apparently rare in Co. Mayo, having been 

 searched for on many occasions, but found once only. 



TJlonema rhizophorum Fosl. 



It is most probable that TJlonema is merely a form of M. strangulans 

 occurring on Dumontia, but some curious stages occasionally found make one 

 hesitate to reduce it till the point has been more thoroughly investigated. 



Hecatonema reptans Kylin (= Ectocarpus reptans Kjellm., non Crouan) ; 

 Streblonema reptans De Toni). 



The full synonymy of this species and M. reptans will be given in the 

 Monograph. Suffice it to say here that I have examined Kjellman's type, and 

 there is no doubt that it should be placed in Hecatonema. It is not 

 uncommon in our district on Cladophora sericca and C. rupestris. 



H. speciosum Cottou, comb. nov. (= Myrionema speciosum Borg. ; Hecatonema 

 diffusum Kylin). 



The type-specimens of both these plants have been examined ; and it is 

 quite clear that H. diffusum Kylin is an early stage of Borgesen's M. speciosum. 

 Hecatonema is, however, the most suitable genus. The plant is common in 

 the British Isles, especially in spring, and was noted frequently in Clare 

 Island on a variety of plants during both the April trips. 



Microspongium globosum Reinke (= Myrionema globosum Fosl. ; Hecatonema 

 globosum Batters). 

 A difficult species to place ; but when well grown it is evident that it is 

 most suitably located in the genus Microspongium. 



B,J.A. PROC, VOL. XXXI. Q 15 



