DEEP-SEA FISHES. 305 



600 fathoms are inhabited by numerous forms, still strongly 

 reminding us of surface types. To this fauna belong the few 

 Chondropterygians of the deep sea, a Sebastes and Setarches, 

 a Beryx and Polymixia, a Cottus, etc. ; but they are associ- 

 ated with many others which descend to the greatest depths. 

 And before anything lilte a division into bathymetrical zones 

 can be attempted, the observations of the " Challenger " 

 expedition must be confirmed and supplemented by other 

 series of similar systematic observations. One of the most 

 startling conclusions at which we would have to arrive from 

 the " Challenger " observations is, that some of the species of 

 Deep-sea fishes would range from a depth of some 300 fathoms 

 down to one of 2000 fathoms ; or, in other words, that a fish 

 which has once attained in its organisation to that modifi- 

 cation by which it is enabled to exist under the pressure of 

 half a ton, can easily accommodate itself to one of two tons 

 or more, — a conclusion which is not in accordance with ana- 

 tomical facts, and which must be confirmed by other obser- 

 vations before we can adopt it. But if the vertical range of 

 Deep-sea fishes is actually as it appears from the " Challenger '' 

 lists, then there is no more distinct vertical than horizontal 

 distribution of Deep-sea fishes. 



The greatest depth reached hitherto by a dredge in which 

 fishes were enclosed is 2900 fathoms. But the specimens 

 thus obtained belong to a species [Gonostoma microdon), which 

 seems to be extremely abundant in upper strata of the Atlantic 

 and Pacific, and were therefore most likely caught by the 

 dredge in its ascent. The next greatest depth, viz., 2750 

 fathoms, must be accepted as one at which fishes undoubtedly 

 do live; the fish obtained from this depth of the Atlantic, 

 Bathyophis ferox, showing by its whole habit tha* it is a form 

 living on the bottom of the ocean. 



The fish-fauna of the deep sea is composed cliiefly of 

 forms or modifications of forms which we find represented at 



X 



