1890-91.] 
Chairman’s Opening Address. 
17 
study of Palseophytology, and has sought to determine the affinities 
of palaeozoic genera and species with those of existing forms. With 
this view he has described the fructification of a number of carboni- 
ferous ferns and lycopods. He has compared the plant remains of 
several British coalfields with each other, and with those of the 
coalfields of other countries. The most important results of his 
investigations have appeared in our Transactions. 
On the Occurrence of Sulphur in Marine Muds and 
Nodules, and its bearing on their Mode of Forma- 
tion. By J. Y. Buchanan, Esq., F.R.S. 
(Read December 1, 1890.) 
In the first section of the cruise of the “ Challenger,” that from 
Tenerife to Sombrero, the existence was established of deep-sea 
muds, perfectly free from carbonate of lime, consisting mainly of 
silicates mixed with ochreous material, principally hydrated oxides 
of iron and manganese, and of local concentrations of these materials 
in the form of nodules and of coatings or incrustations on dead 
calcareous matter. The qualitative composition of these concentra- 
tions was carefully determined, and it was particularly noted that 
whether in the form of nodules or of incrustations they were aggre- 
gations of the general materials of the bottom, and not concretions 
or coatings of pure hydrous oxides. 
On the section between Bermuda and the Azores some very 
suggestive specimens were got from the bottom on 27th June 1873, 
when the ship dredged in 1675 fathoms in lat. 38° 18' N., long. 34° 
48' W. A number of light-coloured concretions were brought up 
which were much perforated by worm-holes, the walls of which 
were all stained blackish brown. The substance of the concretions 
consisted of carbonate of lime and silicates, and the black lining 
of the holes was peroxide of manganese. The various specimens 
obtained on this occasion showed the deposition of oxide of man- 
ganese in various stages, from those which showed only specks or 
stains to those containing a considerable percentage.* The most 
remarkable fact, however, was the close association of the oxide of 
manganese, especially at its first appearance, with the work of 
* They are described in my report, Proc. Roy. Soc., 1876, vol. xxiv. p. 606. 
VOL. XVIII. 31/12/90 B 
