Geology and Mineralogy. 223 



In its longer diameter and mottled with black, red and brown 

 -colors. It was overgrown with sponges, corals and annelids. 

 Imbedded in the concretion were two Sharks' teeth resembling 

 those of Lamna, the largest 2|- in. long and 1 in. across the base. 

 Mr. Murray says that " this tooth is similar to many found by 

 the "Challenger" in great numbers in the greater depths of the 

 central Pacific, frequently forming the centers of manganese 

 nodules ;" but while those of the Pacific always had the interior 

 removed, the vaso-dentine of these teeth was well-preserved, as 

 in the fossil specimens of South Carolina and Malta. This con- 

 cretion has a brecciated character ; the fragments were cemented 

 by calcium carbonate and manganese oxide, the latter every- 

 where penetrating the mass ; and in the mass were remains of 

 pelagic and other calcareous Foraminifera, of Pteropods, and 

 fragments of Echinoderms, with many small, rounded glauconite- 

 like phosphatic grains. Very similar masses were dredged by 

 the " Challenger," especially off the Cape of Good Hope but also 

 elsewhere. Phosphatic nodules were found in depths less than 

 1500 fathoms, but not in deeper deposits far removed from land. 

 The above concretion, analyzed by M. Klement, afforded Phos- 

 phoric acid 23-53, carbon dioxide 15*56, sulphur trioxide 2*29, 

 fluorine 2*28, chlorine 0*16, lime 52*15, magnesia 1*01, loss on 

 ignition 3*15, insoluble residue 0*52 = 100*65. 



At a depth of 457 fath. (2742 ft.) in 33° 19' K, 76° 12' 30' W. 

 (bottom temperature 40° F.) a greenish coherent mud was ob- 

 tained, 59*43 p. c. of which were calcareous; of the mud, 20 p. c. 

 were mineral grains, quartz, hornblende, feldspars, glauconite and 

 glassy fragments; 5 p. c. were siliceous organisms, Diatoms, 

 Radiolarians, Sponge-spicules ; and 15*57 were argillaceous mate- 

 rial, with Diatoms, Sponge-spicules and fine mineral particles. 



The calcareous Foraminifera included (those that were common 

 are marked with an asterisk) (a.) Pelagic: * Globigerina (Orbu- 

 lina) universa, * G. bulloides, G. conglobata, * G. bidloides var. 

 triloba, G. ceguilateralis, G. sacculifera, * G. dubia, * G. rubra, 

 * Cadeinanitida, Sphceroidina dehiscens, *Pidlina obliquilocidata, 

 *Pulvimdina Menardii, *id. var. tumida, *id. var. fimbriata, P. 

 Micheliniana, P. Canariensis ; (b.) Bottom-living species : Bilo- 

 culina ringens, Miliolina seminulum, Pulimina marginata Poly- 



morphina ?, Uvigerina pygmwa, * Sphceroidina bulloides, 



Pullinia sphceroides, Truncatulina lobatida, T. f, Nonionina 



umbilicidata, Nodosaria communis, N. laevigata. 



(3.) Off the shores of the Greater and Lesser Antilles. — The 

 dredgings were rather near the coasts and at various depths to 

 over 2000 fathoms, but mostly under 1000. The mineral particles 

 were chiefly from volcanic rocks ; a few only were from other 

 rocks of the species quartz, tourmaline, mica, epidote ; glauconite 

 and phosphate grains were rare. The percentage of calcareous 

 material was high, frequently 70 or 80 p. c. (in one case, 90*24 

 p. c.) except where the shores were of volcanic rocks without 

 reefs, and here they were volcanic muds. For the most part they 



