extending far from the axillae. The cellular substance of which the recep- 

 tacle is composed is dense and uniform, but the greater part is hollowed 

 out into spore-cavities which communicate with the surface by a pore, one 

 cavity lying under each of the bead-like warts of the receptacle. These cavi- 

 ties are lined with long simple filaments {paranemata), among which both 

 spores and antheridia are found. The spores are narrow-obovoid, each sur- 

 rounded by a pellucid perispore ; the antheridia ovate, bright yellow, and 

 attached, in a sort of raceme, to branching filaments. The substance is co- 

 riaceous, somewhat horny when dry. The colour is a dark olive-brown, 

 becoming darker in the herbarium. 



One of the many remarkable Fucoids of Australia discovered 

 by Dr. R. Brown, and first figured in Turner's ' Historia Fuco- 

 rum.' There is an extraordinary resemblance in the whole de- 

 velopment of the frond between this plant and Scytothalia dory- 

 carpa, Grev. (to be figured in our next number) ; so great that 

 both Montagne and Kiitzing regard them as referable to the same 

 genus. I rather follow Greville and Agardh, in keeping them 

 apart, if the principles on which genera have been established 

 among the Fucacece are to be observed, for there is a remarkable 

 difference in the structure of their receptacles. Besides this dif- 

 ference in inflorescence, a minor character exists, which can only 

 be observed in the living plant, but which is indicative of a dif- 

 ference of nature. When a Scytothalia is steeped in fresh-water 

 it throws out, like a Fucus, an immense quantity of slimy gela- 

 tine, but this is not the case with Seirococcus. 



The geographical distribution of these plants is also different ; 

 the Seirococcus being a genus of eastern, and the Scytothalia of 

 western Australia. 



Fig. 1. Seirococcus axillaris ; portion of a branch, — the natural size. 2. 

 Some of the marginal receptacles. 3. Semi-cross-section of a receptacle, 

 showing one of the immersed spore-cavities containing spores and parane- 

 mata. 4. A spore and paranema removed : — the latter figures more or less 

 magnified. 



