Oceanic Ichthyology, a treatise on the deep-sea and pelagic fishes of the world, based chiefly upon the collections made by the steamers Blake, Albatross, and Fish Hawk in the northwestern Atlantic

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 meaning of the term, as proposed by Hensen, was limited by ILeckel. Home of these, which occur at considerable depths, we call "bathypelagic."

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 condition 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 ichthyologists 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

When this volume was begun, it was not intended to include so large a field within its scope, but unexpected delays have brought us to a time when there is an entire discontinuance of deep-sea work, and when the final ichthyological results of all past expeditions have been published.

In 1885 Prof. Collett, of the University of Christiania, published a volume upon the fishes of the Norwegian North Sea Expedition. In 1887 Dr. Gunther, of the British Museum, published his great work on " The Deep-Sea Fishes of the Challenger Expedition ". In 1888 Dr. Yaillant, of the Museum of Natural History in Paris,reported upon the Deep-Sea Fishes of the Travailleur and Talisman Expedition, and in the same year Mr. Alexander Agassiz presented his admirable "Contributions to American Thalassography", in which, for the first .