EEPORT ON THE RADIOLARIA. cli 



obtained to the east of Madagascar, and next in those from the neighbourhood of the Cocos Islands. 

 I take this opportunity of expressing my thanks to Captain Eabbe for the liberality with which he 

 placed all this valuable material at my disposal. 



D. On my voyage from Aden to Bombay, and thence to Ceylon (1881), and especially on my 

 return journey from Ceylon, between the Maldive Islands and Socotra (1882), I carried on a number 

 of experiments with a surface net, which yielded a rich fauna of pelagic animals, and among them 

 many new species of Eadiolaria, for observation. On several nights when the smooth surface of 

 the Indian Ocean, unrippled by any wind, shone with the most lovely phosphorescent light, I drew 

 up water from the surface with a bucket, and obtained a rich booty. A number of other new 

 species of Eadiolaria from very various parts of the Indian Ocean I obtained from the alimentary 

 canal of pelagic animals, such as Medusie, Salpte, Crustacea, &c. Although the total number of 

 Eadiolaria known to me from the Indian Ocean is much less than from the Atlantic and Pacific, 

 there are several new genera and numerous species among them, which show that a careful study 

 of this fauna will be of wide interest. 



231. Fauna of the Atlantic Ocean. — The Atlantic Ocean in all parts, of which the 

 pelagic fauna has been examined, has shown the same constant presence of Eadiolaria, 

 and in certain parts of its abyssal deposits a larger or smaller quantity of different types 

 belonging to this class ; on the whole, however, its Radiolarian fauna is inferior to that 

 of the Pacific, and probably also to that of the Indian Ocean, both in quantity and 

 quality. Pure Radiolarian ooze, such as is so extensively found on the floor of the Pacific, 

 and in certain places in that of the Indian Ocean, has not yet been found in the Atlantic 

 (see § 237). The red clay, too, of the deep Atlantic does not seem to be so rich in 

 Eadiolaria as that of the Pacific ; nevertheless, the number of species peculiar to the 

 Atlantic is very large, and at certain points the abundance of species as well as of indi- 

 Ndduals seems to be scarcely less than in the Pacific. This is especially true of the eastern 

 equatorial zone not far from Sierra Leone, Stations 347 to 352 (see note A) ; also of the 

 South Atlantic between Buenos Ayres and Tristan da Cunha, Stations 324, 325, 331 to 333 

 (see note B) ; and, lastly, in the North Atlantic in the Gulf Stream and near the Canarj^ 

 Islands (see note C). The fauna of the latter agrees for the most part with that of the 

 Mediterranean (see note D). In addition to the material collected by the Challenger, 

 other deep-sea investigations have furnished bottom-deposits from different parts of the 

 ocean, which have proved very rich in Eadiolaria (see note E). Furthermore, since the 

 island of Barbados consists for the most part of fossil Eadiolarian ooze, it is very 

 probable that at certain parts of the tropical Atlantic true Eadiolarian ooze, like that of 

 the Pacific and Indian Oceans, will eventually be found in depths between 2000 and 3000 

 fathoms, perhaps over a considerable area. 



A. The tropical zone of the eastern Atlantic seems to be especially rich in peculiar Eadiolaria 

 of different species. This is shown by numerous preparations from the surface, and from various 

 depths (between lat. 3° S. and 11° N., and long. 14° W. to 18° W.), which were made towards the 



