REPORT ON THE RADIOLARIA. clvii 



ooze in the fossil condition. Mixed Radiolarian ooze is the name given to those deposits 

 in which the Radiolaria exceed any of the other organic constituents, although they do 

 not make up half the total mass. To this category belong a large number of the Chal- 

 lenger soundings which are entered in the Station list either as red clay or Globigerina 

 ooze. Such mixed Radiolarian ooze has been discovered (A) in the North Pacific in an 

 elongated area of red clay extending from Station 241 to Station 245 (perhaps even from 

 Station 238 to Station 253), that is, at least, from long. 157° E. to 175° E., between 

 lat. 35° N. and 37° N. ; (B) in the tropical Central Pacific in the Globigerina ooze of 

 Stations 270 and 271. The ooze from the latter station, situated almost on the equator 

 (lat. 0° 33' S., long. 151° 34' W.), is specially remarkable, for it has yielded more new 

 species of Spumellaeia and Nassellaria than any other Station, not excluding even 

 the neighbouring Stations 268, 269, and 272. Probably such mixed Radiolarian ooze 

 is very widely distributed in the depths of the ocean, as, for example, in the South 

 Pacific (Stations 288, 289, 300, and 302), and in the Southern Ocean (Stations 156 to 

 159); also in the South Atlantic (Stations 324, 325, 331, 332) and in the tropical 

 Atlantic (Stations 348 to 352). When carefully purified and decalcified by acids, Radio- 

 larian ooze appears as a fine shining white powder ; in the raw state it is yellowish or 

 reddish, sometimes reddish-brown or dark brown in colour, according to the quantity of 

 oxides of iron, manganese, &c., which it contains. Calcareous skeletons (especially the 

 tests of pelagic Foraminifera) do not occur at all or only in very minute quantities in 

 pure Radiolarian ooze from more than 2000 fathoms, whilst specimens of mixed ooze 

 often contain considerable quantities of them. 



Pure Eadiolarian ooze was first described by Dr. John Murray as regards its peculiar nature 

 and composition under the name "Radiolarian ooze" (1876, L. N. 27, pp. 525, 526); compare also 

 Sir Wy villa Thomson (The Atlantic, L. N. 31, vol. i. pp. 231-238), and John Murray (Narr. Chall. 

 Exp., L. N. 53, vol. i. pt. ii. pp. 920-926, pi. n. fig. 2). The different specimens of pure Piadiolarian 

 ooze obtained by the Challenger from the Pacific, and handed to me for investigation, are from 

 depths of from 2250 fathoms to 4475 fathoms, and may be divided according to their composition 

 into three different groups : — I. The Eadiolarian ooze of the Western Tropical Pacific, Stations 225 

 and 226, from depths of 4475 and 2300 fathoms (lat. 11° N. to 15° N., and long. 142° E. to 144° E). 

 II. The Eadiolarian ooze of the northern half of the Central Pacific, Stations 265 to 269, from depths 

 of 2550 to 2900 fathoms. III. The Eadiolarian ooze of the southern half of the Central Pacific, 

 Stations 270 to 274, from depths of 2350 to 2925 fathoms. A fourth group would be constituted 

 by the Eadiolarian ooze from the Philippines, which was brought up by Brooke in 1860 near the 

 Marianne Islands from 3300 fathoms, and described by Ehrenberg (Monatsber. d. k. preuss. Akad. 

 d. Wiss. Berhn, 1860, p. 765). The Diatom ooze, too, found by the Challenger in the Antarctic 

 regions (Stations 152 to 157) is in some parts so rich in Eadiolaria that it passes over into true 

 Eadiolarian ooze. Eegarding the Eadiolarian ooze from Zanzibar, obtained by Captain Pullen in 

 1859 from 2200 fathoms (§ 230), we have only the incomplete communications of Ehrenbeig 

 (L. N. 24, p. 147). A more accurate knowledge of these deposits from the Indian Ocean, and of 



