Plate 4. 



Fig. 9. Typical nodule from Station 13, September 5, 1899, lat. 9° 57' N., long. 137° 47' W., 

 depth, 2630 fathoms. Nodules of this size are very abundant at this station. 

 The shape and surface characters are also highly characteristic, so that the 

 nodules all look exactly alike. Note the resemblance to the nodule from Station 

 4711 shown in PI. 2, Fig. 4. 



Fig. 10. Spherical nodule from Station 173, November 4, 1899, lat. 18° 55' S., 

 long. 146° 32' W., depth, 2440 fathoms, where the spherical shape is the most 

 commonly met with. This photograph is given to show the remarkable surface 

 characters. The numerous minute, closely-set mammillae, giving the surface 

 its coarse shagreen-like appearance, are characteristic of the nodules dredged 

 at this point, and are to be found on all of them, whatever their shape and size 

 may be. 



Fig. 12. Section through a flat, slab-like nodule from Station 173. This figure shows, 

 not very distinctly, the central core of palagonite, of one of the flat, slab-like 

 nodules. The shape of the nodule corresponds to that of the nucleus. 



Fig. 13. Section of nodule from Station 173. A nucleus of palagonitic substance as shown 

 here is present in all the nodules. The photograph also shows white specks 

 of palagonitic substance distributed throughout the thick layer of manganese- 

 iron oxides. These specks may be seen specially well on the fractured portion, 

 friction having more or less obliterated them on the cut surface. The dense 

 compact nature of the layer of oxides is well displayed. 



Fig. 14. Section through a small nodule from Station 173. This figure shows the rela- 

 tively very large nucleus of the small nodule, sliced and mounted on a slide. 



