16 "ALBATROSS" EASTERN TROPICAL PACIFIC EXPEDITION. 



It is impossible at present to indicate the geographical distribution of the 

 Diatoms, Dinoflagellates, Tintinnids and Radiolarians thus far collected in 

 our pelagic hauls. The same genera of these groups are constantly occurring 

 at very distant points and their distribution seems mainly charactei-ized by 

 the association of varying numbers of specimens of the same genera and 

 species. But undoubtedly a closer tabulation of the species of these groups 

 may lead to a general conception of their geographical distribution over the 

 area of the Pacific explored by the "Albatross." 



The principal genera of Diatoms met with are Coscinodiscus, Asteromphalus, 

 Planktoniella, Rhizosolenia, Synedra, Gossleriella, Eucampia, Thalassiothrix, 

 Biddulphia, Euodia. 



Of the Tintinnids: Tintinnus, Undella, Dictyocysta, Amphorella, Cytta- 

 rocylis, Codonella, Poroeca are the principal genera found. 



Coccoliths, Coccospheres, and Rhadospheres, occurred in the whole area' 

 explored by the " Albatross." Noctiluca and Pyrocystis were not uncommon. 

 Challengeridae, Challengeron, Tuscaroridae and Tuscarusa were obtained in 

 nets sent down to 150 and 300 fathoms, and from the surface. Trichodes- 

 miuin, Halosphaera, and other pelagic Algae were most common. 



Among the Radiolarians the following genera have been noted, many 

 of which have been described as living at great depths while in reality they 

 are only the dead carcasses of types living at the surface or close to it and 

 gradually falling to the bottom : 



Collozoum Rhopalastrum Cyrtophormis 



Belonozoum Concliidiuni Lithostrobus 



Cenosphfera Litholophus Lithomitra 



Ethmosph?era Acanthonia Eucyitidium 



Odontosplifera Acanthostaurus Lithocampe 



Chtt'iiicosphiBra ("Speciesdescribedby Belonostaui'us Aulactinium 



ri- 1 1 Haeckel as found in r/ , * i ^i 



biphonosplisera '2500 fathoms in Cen- Zjgostaurus Aulocautha 



Trypanosphrera I'"'''' Pacific. Amphibelone Sagosphtera 



Soleno.sphffira Perispyris Aulosphtera 



Hexastylus Nephros]3yris Cannosphsera 



Hexacontium Litharaehniuni Challengeron 



Echinonnna Carpocanistrum Challengeria 



Cromyomma Cornutella Cadium 



Pityomma Tripocyrtis Mednsetta 



Ellipsostylus Lychnocanium Euphysetta 



Stylatractus Carpocaniuni Circoporus 



Spongocore Sethoconus Tiiscarora 



Porodiscus Dictyoceras Tnscarnsa 



Euchitonia Theocalyptia Tuscaiidium 



