18 Proceedings of the Royal Society of Edinburgh. [Sess. 
that species possessing or lacking it are regarded in the same light ; and 
that much more evidence is required before it can be held that the character 
is evanescent within the limits of a single species — in spite of the identifica- 
tions of Jaderholm (1905) and myself (1907), misled by Allman’s incomplete 
description, and of Vanhoffen (1910), who suggests that the nematophores 
first appear in older branches. But even the shortest branchlets in the 
Fig. 4. — Part of branch of Halecium macrocejohalum t from off Coats Land, 
previously recorded as Halecium robustum. x 25, 
Antarctic specimens in the present collection bear nematophores. On 
account of this character, which appears to me to be definite and decisive, 
I follow Billard in transferring the species to genus Ophiodes. 
The species, lacking nematophores, which was collected by the Scottish 
Antarctic Expedition off Coats Land and at St Helena, and was referred 
by me (1907) to Halecium robustum ( = arboreum ), Allman, must now be 
separated from this nematophore-bearing species. I therefore rank it with 
Halecium macrocephalum, Allman, 1877, a species with trophosome similar 
