clii THE VOYAGE OF H.M.S. CHALLENGEE. 



end of the cruise. Unfortunately no bottom-deposits were obtained from the most important stations 

 (except Nos. 346 and 347, depths 2350 and 2250 fathoms) in this region ; at these the deposit was 

 a Globigerina ooze containing numerous different species of Eadiolaria. 



B. In the South Atlantic, between Buenos Ayres and Tristan da Cunha (between lat. 35 S. and 

 43 S., long. 8 W. and 57 W.) there appears to be a long stretch covered partly with Globigerina 

 ooze (Stations 331 to 334), or red clay (Stations 329, 330), partly with blue mud (Stations 318 to 328), 

 which contains not only large masses of individuals but numerous peculiar species of SPUMELLARIA 

 and NASSELLARIA. The preparations from the surface-takings of this region are also rich in these, 

 as well as in peculiar PH^ODAEIA. 



C. The northern part of the Atlantic appears on the whole to be inferior to the tropical and 

 southern portions as regards its richness in Eadiolaria, and from the western half more especially, 

 only few species are known. From my researches at Lanzerote in 1866-67, it appears that the 

 pelagic fauna of the Canary Islands is very rich in them, as is also the Gulf Stream in the neigh- 

 bourhood of the Fseroe Channel, according to the investigations of John Murray (see his Report 

 on the " Knight-Errant" Expedition, Proc. Eoy. Soc. Edin., vol. XL, 1882). 



D. The Eadiolaria of the Mediterranean are of special interest, because almost all our knowledge 

 of these organisms in the living conditions and of their vital functions has been derived from 

 investigations conducted on its shores. Johannes Mliller laid the foundation of this knowledge by 

 his investigations at Messina, and on the Ligurian and French coasts at Nice, Cette, and St. Tropez 

 (L. N. 10). The many new Eadiolaria which I described in my Monograph (L. N. 16, 1862), were 

 for the most part taken at Messina, the place which possesses a richer pelagic fauna than any other, 

 so far as is yet known, in the Mediterranean. Other new species I found afterwards at Villafranca 

 near Nice, in 1864 (L. N. 19), at Portofino near Genoa (1880), at Corfu (1877), and at other points 

 on the coast. In Messina also, Eichard Hertwig collected the material for his valuable treatise on 

 the Organisation of the Eadiolaria (L. N. 33), after he had previously made investigations into their 

 histology at Ajaccio in Corsica (L. N. 26). Lastly, at Naples, Cienkowski (L. N. 22) and Karl 

 Brandt (L. N. 38, 39, 52) carried out their important investigations into the reproduction and 

 symbiosis of the Eadiolaria. With respect to the character of its Eadiolaria, the Mediterranean 

 fauna is to be regarded as a special province of the North Atlantic. 



E. Among the smaller contributions which have been made towards our knowledge of the 

 Atlantic Eadiolarian fauna, the communications of Ehrenberg on the deposits obtained in sounding 

 for the Atlantic cable, and on the Mexican Gulf Stream near Florida, deserve special mention 

 (L. N. 24, pp. 138, 139-145). 



232. Vertical Distribution. The most important general result of the discoveries of 

 the Challenger, as regards the vertical or bathymetrical distribution of the Radiolaria, is 

 the interesting fact that numerous species of this class are found living at the most 

 various depths of the sea, and that certain species are limited to particular bathymetrical 

 zones, i.e., are adapted to the conditions which obtain there. In this respect three 

 different Radiolarian faunas may be distinguished, which may be shortly termed " pelagic," 

 " zonarial," and " abyssal." The pelagic Radiolaria swim at the surface, and when they 

 sink (e.g., in a stormy sea), only descend to a small depth, probably not more than from 



