REPORT ON THE ISOPODA. 163 



the above quoted opinion, though it does not on the other hand render it inapplicable to 

 this group. So very few of the deep-sea species of Isopoda were dredged in any numbers 

 that I cannot say much respecting the number of individuals in the neighbourhood of 

 continents as compared with the number dredged at Stations far distant from any 

 continent ; such facts as are at my disposal do not indicate any very marked distinction 

 in this respect ; Eurycope novee-zelandise, Serolis bromleyana, Serolis nesera, Serolis 

 gracilis, Typhlapseudes nereus, and Arcturus myops, are represented by a considerable 

 number of individuals, and all these species frequent the neighbourhood of continents ; 

 on the other hand, Eurycope sarsii, Arcturus spinosus, Arcturus brunneus and Leiopus 

 leptoclactylus are true "abyssal" forms, and are also comparatively abundant in individuals. 

 Here again the balance of evidence supports Messrs. Murray and Renard, but not in a 

 striking way. 



With regard to the supposed archaic character of the deep-sea fauna the facts at 

 my disposal do not permit of any positive statements. 



GEOGRAPHICAL DISTRIBUTION OF DEEP-SEA ISOPODA. 



One of the most important results of the recent explorations of the deep sea has 

 been to show that it is impossible to mark out any definite regions of the ocean compar- 

 able to the terrestrial distributional provinces ; the same genus, and even the same species, 

 is often represented by individuals in the most widely separated areas ; and this is 

 explained by the similar conditions which must obtain at great depths in all parts of the 

 ocean. Among the Isopoda no great stress can be laid upon the occurrence of the same 

 genus in regions of the ocean widely remote from each other, because among the 

 shallow-water forms many, not to say most genera, are universally distributed ; more 

 important results can evidently be attained by considering the distribution of particular 

 species rather than genera. Bearing in mind the very limited knowledge, comparatively 

 speaking, which we at present have of the deep-sea fauna, the occurrence of five species 

 over a wide tract of the earth's surface is more important than it would appear to be 

 if we judged only by percentages. 



The most widely distributed species is Eurycope fragilis, which ranges from the 

 North Pacific, near to Japan, as far south as lat. 60° S., close to the Antarctic ice- 

 barrier, and to the neighbourhood of the Crozets. 



Two species of Serolis, viz., Serolis antarctica and Serolis bromleyana, have been 

 referred to in the first part of my Report as having a wide horizontal distribution ; 

 the former was dredged off the coast of South America, just under the equator, and 

 again in the neighbourhood of the Crozets ; the latter ranges from off the coasts 

 of New Zealand and Australia to the vicinity of the Antarctic continent. Neotanais 

 americanus inhabits regions so far removed as Station 45, off New York, and Station 



