PLATE XXVIII. 
Fig. 1. Section of manganese nodule from Station 160; 2600 fathoms, Southern Indian Ocean. This micro- 
scopic preparation shows, besides the zonary arrangement, a dendritic structure of the manganese. 
These dendrites are arranged along the radii of the nodule, and the manganese is, as it were, im- 
bedded in a yellowish brown mass of clayey and earthy matters (magnified 37 diameters). 
Fig. 2. Section of manganese nodule from Station 160 ; 2600 fathoms, Southern Indian Ocean. Around the 
indefinite white-coloured nucleus there is a concretionary arrangement of the manganese in the 
form of dendrites ; the radiate structure is not, however, well marked. The large ovoid body 
occupying most of the figure was’ probably the primary form of the original nucleus (magnified 37 
diameters). 
Fig. 3. Section of manganese nodule from Station 285; 2375 fathoms, South Pacific. This figure shows a 
nodule vith several concretionary centres, consisting of organic particles or fragments of palagonite 
or other volcanic rocks. The depositions which had commenced arovmd these several centres 
ultimately became united into a single nodule by the formation of successive layers of manganese 
(magnified 37 diameters). 
Fig. 4. Section of manganese nodule from Station 160; 2600 fathoms. Southern Indian Ocean. This figure 
shows the dendritic and zonary arrangement of the manganese (magnified 37 diameters). 
Fig. 6. Section of manganese nodule from the same station, showing a dendritic arrangement of the man- 
ganese, in which the radiate structure is not well marked, but presenting zones in which the 
colouring matter has accumulated (magnified 37 diameters). 
