PELAGIC ANIMAL LIFE 



585 



Phronima. 



■ 4^3- 



(From Steuer. ) 



great depths, and they were consequently supposed to be bottom-dwellers. 

 Subsequently the Prince of Monaco, and later the " Valdivia," took in 

 pelagic tow-nets a number of forms belonging chiefly to the family 

 Sergestidae, and to the genera AcanthepJiyra, Notostomus, and Eryoneicus, 

 all of which were thus proved to lead a pelagic life. The " Valdivia " 

 took Sergestes in a haul with a closing net from 5000 to 4000 metres, and 

 Chun states in his narra- 

 tive of the cruise that 

 whenever the vertical nets 

 reached deep water this 

 genus never failed to 

 appear in the hauls. 



During the Atlantic 

 cruise of the " Michael 

 Sars " we obtained large 

 red prawns in such abund- 

 ance (several litres per 

 haul) as to prove that 

 these animals play a more 

 important part in pelagic 

 life than was previously 

 supposed. Our catches are 

 also of special interest, be- 

 cause their study has thrown new light upon the vertical distribution 

 of the different species. We may here mention some of the most 

 important forms recorded by Oscar Sund, who is describing this group. 



Of pelagic decapoda more than forty species were taken during our 

 expedition, but the great bulk is made up of about a dozen species, each 

 of which has a wide geographical range, being regularly caught at all 



stations over vast areas. Most of these 

 common species, which will be dealt 

 with later on, present peculiarities in 

 their biology and distribution. 



Most of the pelagic decapoda be- 

 long to the more primitive divisions of 

 the group, viz. Sergestidae, Peneidae, 

 Pasiphaeidae, and Hoplophoridae, but 

 a truly pelagic Pandalid {Plesionika 

 nana, n. sp.) was taken at most of 

 the stations from Spain to Newfound- 

 land. 



The genus Acanthephyra of the Hoplophoridae (see Plate III. 

 Chapter X.) includes large red prawn-like forms, of which no less than 

 eight different species were taken. On the section between Newfoundlarid 

 and Ireland the two species A. purpurea and A. multispina were m 

 special abundance. 



Before the cruise of the "Michael Sars" only fifteen individuals 

 belonging to the genus Notostomus, representing no less than thirteen 

 species, had been recorded. We procured nineteen individuals in the 

 North Atlantic belonging to five species, of which four are new to 



Fig. 424. 



Parathemisto oblivia, Kroyer (f ). 



(From Sars. ) 



