EUPHAUSIACEA. 295 



THE DISTRIBUTION OF THE EUPHAUSIACEA. 



As already stated, the Agassiz Expedition 1904-1905 in the tropical and 

 subtropical East Pacific secured thirty-nine species of the order Euphausiacea, 

 thus a Uttle more than half of the species known from all Oceans together. 

 Among these thirty-nine species nineteen are at present known both from the 

 Atlantic and from the Indian Ocean, eight from the Atlantic, but not from the 

 Indian Ocean, five from the Indian Ocean (in the main from the Indian Archi- 

 pelago) but not from the Atlantic; thus thirty-two of the thirty-nine of the 

 species enumerated here from the East Pacific are known from at least one of 

 the two other great Oceans. And I think that in no other order of Invertebrates 

 82 p. c. of the species known from the warm area of the East Pacific are also 

 known either from one of the two other Oceans or from both! Seven species 

 remain; among these one, viz. Euphausia gibba G. O. S., is also known from 

 the West Pacific (between Api and Cape York), and a second, E. pacifica H. J. H. 

 is widely distributed in the North Pacific and has been taken several times 

 near Japan and Corea. Deducting these forms the following five species: — 

 Nydiphanes simplex H. J. H., Euphausia eximia H. J. H., E. distinguenda 

 H. J. H., E. lamelligera H. J. H., and E. mucronata G. O. S. are known only 

 from the East Pacific, but one among them E. mucronata has also been captured 

 off Chile, thus more southwards, and a second, Nydiphanes simplex, is known 

 from the Gulf of California and another location at Lat. 351° N. Three species 

 remain hitherto not known to me from any Station outside the area explored 

 in 1904-1905! 



As to the distribution within the area explored in 1904-1905 of the species 

 taken at nurnerous localities I do not venture to say a great deal; an investi- 

 gation of thic kind must be connected with a detailed study of currents and tem- 

 peratures. For the majority of the species in question I have in the passage on 

 distribution pointed out the limits of the occurrence within the area explored, 

 but I do not venture to attempt a more general treatment. Only one interest- 

 ing detail I may call attention to. When two closely allied species, as Euphausia 

 diomedeae Ortm. and E. mutica H. J. H., Nematoscelis microps G. 0. S. and N. 

 gracilis H. J. H., were both taken at numerous Stations, they were only taken 

 together at some few Stations, and in one part of the area one of such two alUed 

 species was very common but quite wanting in another part, while the second 

 species, which was absent in the first part, was common in the other. 



Our knowledge of the bathymetrical occurrence and distribution is rather 



