PLATE IX. 
Fig. 1. Fourth part of a large nodule from the North Pacific (natural size) ; the nodule when dredged measured 
31 X 20 X 6 centimetres. There is a great difference between the two large faces, the one figured 
being the upper surface. The under surface, that which rested on the clay of the bottom, is rough 
and consists of numerous closely-set mammillae, which are more numerous towards the outer 
edges. The upper surface is much smoother, and the reliefs of the mammillae rounded and 
softened. Small pieces of pumice that have fallen on the upper surface are cemented to it by 
manganese depositions, and in the same way a specimen of Nodosaria can be seen cemented to it 
by layers of manganese. In addition, there were attached to the upper surface : four specimens of 
Stej)ka>ioscyphus, a Tubularian, two Actinians, a Serpula, two Polyzoons, and many Rhizopod tubes 
or rhizomes of a Hydroid. Attached to the vmder surface at the edge was an Annelid with a 
muddy tube. The white central part may be regarded as an elongated nucleus with hollow spaces 
filled by clayey matter ; it is hard, but can be scratched with a knife. It is impossible to suggest 
with any certainty its original nature. The layers of manganese above the nucleus are much 
thicker than those below. Station 253 ; 3125 fathoms. North Pacific. 
Fig. la. End portion of the same nodule, from which the manganese has been removed by concentrated 
hydrochloric acid (natural size). The way in which some of the inner layers terminate at the 
edge suggests that this fragment may at one time have been part of a larger mass. 
Fig. 2. Under surface of nodule from the Central Pacific (natural size). It is formed on a large Carcharodon 
tootli, and takes roughly the form of that triangular body ; it might be said that there are three 
centres of concretion, one at each corner of the triangle. The upper surface is much smoother than 
the under. Station 274 ; 2750 fathoms. Mid Pacific. 
Fig. 3. Compact nodule from the South Pacific (natural size). It is deeply mammillated, and in the hollows 
lietween the mammillffi there is a rough, iiTegular Rhizopod tube. The upper part of the figure 
shows how the nodule breaks into concentric zones. Station 289 ; 2550 fathoms. South Pacific. 
Fig. 4. Sections of manganese nodule from the North Pacifie, one half being demanganesed to show the 
structure (natural size). The nucleus is yellowish, and apparently was originally a piece of pumice ; 
this is surrounded by concentric layers, some of which contain much more manganese than others. 
It will be noticed that, with the growth of the nodule, secondary nuclei have been embraced by 
the concentric layers. There is an indication of radial as well as concentric structure. Station 
248 ; 2900 fathoms. North Pacific. 
Figs. 5 and 6. Sections of nodules from the Central Pacific (natural size). The nucleus is small and surrounded 
by black undulating zones or lines superposed the one upon the other. In fig. 6 the face is 
demangane.sed by concentrated hydrochloric acid to bring out the structure. Station 274; 2750 
fathoms, klid Pacific. 
Fig. 7. Section of a round nodule from the North Pacific (natural size). In this case the cut face of the 
nodule has been demanganesed by concentrated hydrochloric acid, which leaves a clayey skeleton 
showing well the structure of the nodule. Three zones can be recognised : first, the nucleus ; 
second, a zone around this without definite structure ; and third, an external zone of concentric 
layers. Station 252 ; 2740 fathoms. North Pacific. 
Fig. 7a. Portion of the same, showing the external zone with concentric layers (magnified 25 diameters). 
Here the intimate structure is seen; the empty spaces are those that were occupied by the 
manganese, and the figure shows the interpenetration of earthy and clayey matters. 
Fig. 8. .Section of nwlule from the South Pacific, the face of which has been demanganified to show the 
structure (natural size). Tliere is a hard nucleus of volcanic rock, surrounded by a zone without 
any alternating layers, around which arc concentric layers of the u.sual form. Station 276 ; 2350 
fatlioms. South Pacific. 
Fig. 9. No<lule from the South Pacific (natural size). The surface has been treated with concentrated hydro' 
chloric acid to remove the manganese ; the clayey skeleton that remains is very areolar in 
structure. Station 297 ; 1775 fathoms. South Pacific. 
Fig. 10. Portion of no<lulc from the Central T’ncific (natural size), in which tubes ajiparently of Rhizopods are 
seen between two of the layers of the clayey skeleton that remains after treatment with concen- 
trated hydrochloric acid. Station 274 ; 2750 fathoms. Mid Pacific. 
