OCEANIC ICHTI I YOLOGY. 



INTRODUCTION. 



Orn purpose bus been to present in Oceanic Ichthyology a discussion of all forms 



of fisbes found in the seas of tbe world, both pelagic species and those occurring at deptbs 

 greater than 500 feet, especial prominence being given to those species which arc found in 

 tbe Atlantic Ocean, most of which we have bad opportunity to study. All oceanic fishes 

 are included, partly because it is not yet possible to distinguish strictly between the two 

 classes, and partly because the pelagic forms have, in part at least, been mentioned in the 

 discussions by all previous writers on " deep-sea fishes." 



By Oceanic fishes we mean those deep sea and pelagic species which dwell in the open 

 ocean tar from the shore, either at the surface, at the bottom, beyond a depth of 500 feet, or, 

 if such fishes there be, the intermediate zones. 



Oceanic Ichthyology is that branch of ichthyology which is concerned with their study. 



Deep-sea fishes are those which are found at a depth of 1,000 feet or more, without 

 reference to the question whether or not they also occur in shallower water. The limit of 

 500 feet is taken for convenience in the study of the origin of local deep-sea faunas. The 

 limit of 100 fathoms is that ordinarily in use. Tbe Eeports of the Challenger class as 

 '•deep-sea deposits" all those below 100 fathoms depth. Tbe zone between the litteral 

 zone, and the bathybial zones, 500-1000 feet, is called the '•hcmibathybial zone" 



rdagic fishes are those which live far from laud and at a distance from the bottom, 

 rarely approaching the shore except when driven by wind or current. It is these which 

 are most closely associated with the "Plankton," and were included in it before the mean- 

 ing of the term, as proposed by Hensen, was limited by ILeckel. Home of these, which 

 occur at considerable depths, we call "bathy pelagic." 



We cannot claim that in the present memoir we have brought forward any conclusions 

 which are new to science, though a great number of new facts are recorded. We hope, 

 however, that we have succeeded in the attempt to bring the information which we have 

 ourselves been able to obtain into proper relationship with the mass of similar knowledge 

 already recorded, and that our descriptions are so accurate and full that the deterioration 

 or loss of the material studied, much of which was in very fragmentary and precarious con- 

 dition when it came to us, may not be entirely disastrous. We have tried to assemble all 

 existing data about oceanic fishes and to arrange them in such a manner that they may be 

 serviceable to naturalists in other. fields for comparison and study, as well as to ichthyolo- 

 gists for ready reference, when at a distance from the rather extensive group of books which 

 must now be consulted even for the casual identification of a deep-sea fish. We have also 

 endeavored to sum up the conclusions reached by previous students before incorporating 

 our own results with those of our predecessors.* 



Note.— I have in preparation and shall booh publish an extended Btudyofthe geographical distribution 



of deep-sea and pelagic fishes, and of the, origin of the several bathybial iisli faunas. 



G. Bkovi \ (...en. i 



in 



