442 THE VOYAGE OF H.M.S CHALLENGER. 



between tlie Prince Edward and Crozet Islands, in the Pacific ofi" the Kermadec, Little 

 Ki, and Philippine Islands. 



In the middle of the oceans, as well as near the continents, Hexactinellids were indeed 

 found, but genei'ally speaking the abundance of species was less at a distance from the 

 mainland, and in the middle of the great ocean basins, than in the neighbourhood of the 

 continents or island groups. 



It is necessary now to pass to the more detailed distribution of the indi\ddual groups 

 in the various seas. 



In the Atlantic 16 species of Lyssacina were found, in the Indian Ocean 11, and 

 37 in the Pacific. 



If we consider again the number of localities at which dredging and trawUng 

 explorations were undertaken, we have the following results : — 



For the 125 dredgings or trawlings in the Atlantic, 16 species of Lyssacina, = 12-9 per cent. 



„ 32 ,, „ Indian Ocean, 11 „ „ 34--i „ 



„ 119 „ „ Pacific, 37 „ „ 31-0 



As to Dictyonina, the Atlantic j-ielded 8, the Indian Ocean 3, and the Pacific 

 18 species. And in reference to the number of dredgings and trawlings in the same 

 sea, these figures represent for the Atlantic 6"4 per cent., for the Indian Ocean 9-4 

 per cent., and 15'1 per cent, for the Pacific. 



In regard to the separate families of Lyssacina, the Atlantic yielded 5 species of 

 Euplectellidse, the Indian Ocean 3, and the Pacific 5, that is to say, in reference 

 to the number of dredgings and trawlings, 4 per cent, for the Atlantic, 9 "4 per cent, for 

 the Indian Ocean, and 6 per cent, for the Pacific. And here it should be noted further 

 that the three species of EuplecteUidte found in the Indian Ocean belonged to the 

 genera Holascus and Malacosaccus, i.e., to the subfamily Holascinse, whUe in the 

 Atlantic and Pacific representatives of all the three subfamilies were discovered. Of 

 Asconematid?e the Atlantic yielded only 1 species, while in the Indian Ocean 4, and 

 in the Pacific 3 were found. A reference to the relatively small number of 

 dredgings and trawlings undertaken in the Indian Ocean, proves a special abundance of 

 Asconematidse in this last region. 



The Atlantic yielded 3 species of Rossellidse, the Indian Ocean 4, and the Pacific 

 1 4 species, which mostly belonged to the Crateromorphinae. 



In the Atlantic 7 Hyalonematidie w^ere found, in the Indian Ocean 2, and in the 

 Pacific 13 species. 



In reference to the Dictyonina, if we take all the Uncinataria together in considera- 

 tion of the small number of representatives of the separate families, w^e find that 

 the Atlantic yielded 5, the Indian Ocean 3, and the Pacific 15 species, that is, in 

 reference to the number of dredgings and trawlings, 4 per cent, for the Atlantic, 9 "4 

 for the Indian Ocean, and 12-G for the Pacific. In a comparative survey of the separate 



