MARINE ALG^. 



11 



from its edges about fifty proliferations. The" whole plant is quite sterile, of very- 

 thin texture, and consists of an internal tissue enclosed in a cortex which is mono- 

 stromatic except at the margin. The structure, however, owing to the crushed 

 condition of its interior cells, affords but little clue to the systematic position of the 

 plant, and all our efforts to make the internal tissue swell out to its original dimensions 

 were in vain. We were therefore unable to figure the structure except near the much- 

 thickened margin of the proliferating scrap of old frond mentioned above (fig. 18). 

 The cells of the monostromatic cortex are large (fig. 19). 



In habit it resembles Dumontia, but has not the hollow thallus and filamentous 

 cell-structure of that genus. Our plant has a solid thallus, and for that reason we 

 should not have searched for it under Halosaccion, but strangely enouo-h we find 

 the Cape Adare plant to be apparently identical with H. dumontioides Harv., an 

 undescribed species from the far North. The habit, the thin texture, the mono- 

 stromatic layer of rather large coloured cortical cells, and the permanently collapsed 

 internal tissue are the same in both. The proliferations in Harvey's plant are linear 

 and very long (fig. 20) ; in the Cape Adare plant they are half as long, and are 

 cuneato-linear and tending to be forked at the apex. Dickie (Journ. Linn. Soc. IX. 

 [1867], p. 239) stated that H. dum.ontioides was first described by Prof Harvey 

 from specimens found by Dr. Lyall in Lat. 76° N. We failed, however, to find any 

 published description, and applied to Dr. E. Perceval Wright, Keeper of Harvey's 

 herbarium. Trinity College, Dublin, for information. He kindly replied : — " I think 

 that a description of Halosaccion dumontioides has never appeared. Dr. Lyall's 

 specimens were collected in July, 1853. Harvey was on his Australian tour, 1853-56, 

 and in 1857 was busy with his Phycologia Australica (1858-1863). All our sheets 

 with Lyall's specimens are marked in pencil with the name and ' Harv. MS.' Now 

 when Harvey published a name, he mostly wrote the name in ink on the sheet. On 

 one of our sheets he has written, still in pencil, ' Can this be a var. of H. ranien- 

 taceum ? ' It is strange that J. G-. Agardh did not write to me for a specimen in 

 1876." — that is, before publishing his Epicrisis. 



Harvey, having only dried material to work upon, and being therefore unable to 

 determine the character of the internal tissue, was in doubt as to the affinity of the 

 plant, and placed it in Halosaccion near H ramentaceum. There we should have been 

 compelled to leave it, had we not found a similar crushed tissue and monostromatic 

 cortex in another species, Gracilaria simplex, of which we had received not only dried 

 specimens, but also spirit material, and to which we regard our plant as closely allied. 

 However, none of the specimens of either species have cystocarps, and their systematic 

 position may have to be reconsidered later.* 



Dickie (loc. cit.) records plants collected in Cumberland Sound (66° N. lat.) by 



* Since these lines were sent to press we have seen some very fine Antarctic specimens, collected by Dr. C. 

 Skottsberg during the Swedish South Polar Expedition, which lead us to believe that our Antarctic plant is not 

 fully grown, and is not conspeciflc with Harvey's plant of Q. dumontioides. Dr. Skottsberg will deal with the 

 question in his own report. 



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