38 



when we consider that they sometimes appear (the third 

 especially) as bright spots when entering upon his surface in 

 transit, as I have myself observed ; but this is only for a 

 short distance within the limb. As they advance upon the 

 face of the planet they become dark by contrast — sometimes 

 as black as their shadows. This is accounted for by the vast 

 difference of brightness between the centre and the edge of 

 the planet's disc. This last is, I think, compatible with the 

 supposition of a glowing tall, whose surface lies far within 

 the confines of the vaporous envelope, which alone is visible to 

 us. As to the satellites, we cannot argue anything definitely or 

 positively from them with regard to the question under 

 discussion, as we know next to nothing of their physical 

 condition ; their variable brightness, if nothing else, compels 

 us to rank them among the many unsolved mysteries of 

 astronomy. 



The subject deserves, and I trust will receive, more 

 precise and thorough investigation. 



TASMAKLAN" MOSSES. 

 By R. A. Bastow, F.L.S. 



The illustrated key, accompanying this paper, is prepared 

 chiefly for the use of students, residing in our country dis- 

 trictsj who have not at all times access to the many valuable 

 Botanical works in. the Royal Society's Library. 



The illustrations are, for the most part, drawn from nature ; 

 or, where specimens of the mosses have not been available, 

 the drawings have been taken from standard works on the 

 subject, namely : — " Flora of Tasmania," " Flora of New 

 Zealand," and " Flora of the Antarctic Islands," by Dr. J. 

 D. Hooker, F.R.S. ; " Bryologia Britannica," by William 

 Wilson, Esq.; and "Musci Exotici," by William Jackson 

 Hooker, F.R.A. & L.S., and in the accompanying description 

 of species the following works have also been freely used : — 

 " Bridel, Bryologia Universa ;" " Hooker's Handbook of the 

 New Zealand Flora ;" " Fragmenta Phytographia? Australia?, " 

 by Baron von Mueller; "Musci Austro-Americaui," by 

 Mitten; "Australian Mosses," by Baron von Mueller; 

 " Mitten's Catalogue of Australian Mosses ;" and MSS. 

 from Mr. H. Boswell, of Oxford. 



The genera are all arranged on one large sheet so 

 that the whole may be presented at one view. The draw- 

 ings on the upper half of the sheet are so placed that 



