Clare Island Survey — Marine Algae. 16 117 



hence herbarium botanists have been off' their guard, and have not detected 

 the microscopic characters which are even more striking and important. 



Batters was the first to recognize the species as distinct, In 1897 he 

 received a specimen from Kilkee collected by E. George, and this he identified 

 with the Mediterranean C. elongatum. He did not apparently record the 

 discovery ; but in his " Catalogue " (1902) he lists C. elongatum, and gives 

 Kilkee as the only locality. On my return to London after the first Survey 

 visit, I examined Batters' specimen. In external form it agreed fairly well 

 with small specimens of C. elongatum, and possessed large utricles, as does 

 that species. The Clare Island gatherings differed somewhat ; but it was 

 established beyond question that the two plants were specifically identical. 

 As there was no other European Codiuni to which the species could be 

 referred, the name C. elongatum was accepted, though each subsequent visit 

 rendered the identification more questionable. Occasional mucronation was 

 noted ; but this was regarded as an irregularity. 



During the second season the matter was thoroughly investigated, and 

 herbarium material of all known species of Codium was examined. As a 

 result, the Irish plant was found to be constantly more or less mucronate, 

 and to resemble very closely the Australian plant C. mucronatum J. Ag. As 

 the position of this species in Europe would be extremely isolated, and since 

 the Irish plant was decidedly less mucronate than the Australian, it was at 

 first thought advisable to describe it as a new species. But on further investi- 

 gation it was found that, as far as could be ascertained from dried material, 

 it differed in no important particular from Agardh's species, the Australian 

 gatherings varying largely amongst themselves as to degree of mucronation. 

 Further, the Irish plant differed much less from var. Novae Zelandiue than does 

 that plant from var. tasmanicum, whilst the Calif ornian variety is far and 

 away more distinct. On the othei;hand, it was undesirable, in the present state 

 of our knowledge, to definitely link the European plant with var. Novae 

 Zclandiae. I have therefore described it as a new variety, which may be 

 distinguished from the last-named by the small size of the mucro, and by its 

 partial absence in some cases. 



The drawing on Plate VII shows its robust habit, 1 and on Plate VIII the 

 form and size of the utricles are depicted. Though mucronation may at times 

 be absent, the greater length of the utricles, and the absence of apical 

 thickening, render these structures perfectly distinct from those of 

 C. tomentosum (cf. figs. 1-2 and 3-5). 



'Unless the specimen be carefully dried, the stout character of the branches may be lost, as is the 

 case in many herbarium specimens. On the other hand, it is possible by excessive pressure to 

 give specimens of C. tomentosum the appearance of C. mucronatum. 



