146 THE DEPTH AND MARINE DEPOSITS OF THE PACIFIC OCEAN. 



ramifications appear to be constantly present, spreading from one oxide layer 

 to another through the palagonitic layers. 



Station 31, 19th September, 1899. 

 Lat. 12° 20' S. ; long. 144° 15' W. ; depth, 2700 fathoms. 



About one hundred small manganese nodules and small cakes and slabs of 

 palagonite were obtained at this station. The nodules averaging 1 to 3 cm. 

 in diameter have a distinctive feature, — they are nearly always formed of 

 smaller nodules cemented together; the shape of the composite nodules is 

 therefore very irregular, the component individual parts being angular or 

 bean-shaped. The surface is smooth and takes on a lustre when rubbed. As 

 regards constitution, some of the nodules have an irregular nucleus of palag- 

 onite, round which are successive layers of manganese-iron oxides. Others are 

 most likely the product of the impregnation of a cake of palagonite by the ox- 

 ides. In fact, there are small fragments of palagonitic cakes showing incipient 

 " manganization." Generally speaking, the nodules are not very solid, break- 

 ing easily along the radii ; polished sections also show cracks along the radii. 



The palagonitic nuclei contain more or less decomposed volcanic glass, 

 some of which has still preserved its pellucidity, felspar, and apparently 

 augite. The palagonite is represented either by angular cakes, 2 to 3 cm. 

 in diameter, light brown and rather soft, or by thin slabs (one was 25 mm. 

 by 5 mm.), hard and bright yellow. Both kinds are thinly coated with 

 manganese-iron oxide. The mineral particles contained in these palagonitic 

 cakes and slabs are apparently the same as those extracted from the palago- 

 nitic nucleus of one of the nodules. 



Station 173, 4th November, 1899. 

 Lat. 18° 55' S. ; long. 146° 32' W. ; depth, 2440 fathoms. 

 These nodules, of which three are figured in Dr. Agassiz's preliminary 

 report,^ constitute one of the most remarkable hauls of the cruise. At this 

 station, where the deposit is Red Clay, immense numbers were dredged, vary- 

 ing in size from that of a small hazel-nut to potato-shaped nodules, three or 

 four inches in diameter, and slabs over six inches in length (see PI. 4, figs. 

 10, 12, 13, IJf. ; PI. 5, fig. 11). Although the shape varies, the surface 

 characters are absolutely constant, and belong to a type which was met with 

 only at this particular spot. The surface of all the nodules, large and small, 

 is even, that is to say, not covered with protuberances, but it is not smooth, 



1 Mem. Mus. Comp. Zool., vol. XXVI., Plate, Manganese Nodules, figs. 2-^. 



