304 FISHES. 



jaws, as in Snakes. These fishes- cannot be said to swallow 

 their food, but rather draw themselves over their victim, in 

 the fashion of an Actinia. 



Before the voyage of H.M.S. " Challenger," scarcely thirty 

 Deep-sea fishes were known. This number is now much 

 increased by the discovery of many new species and genera ; 

 but, singularly, no new types of families were discovered: 

 nothing but what might have been expected from our pre- 

 vious knowledge of this group of fishes. Modifications of 

 certain organs, perfectly novel, and of the greatest interest, 

 were found, as we shall see in the " Systematic Part ; " but 

 the most important results of this voyage are that the general 

 character of the abyssal fish-fauna, the abundance of fishes, 

 and the exact depths to which fishes may descend, have been 

 ascertained. 



However, the statements of the depths at which the 

 fishes collected by the " Challenger " were taken cannot be 

 received without some critical examination of each individual 

 species. No precaution was taken to keep the mouth of the 

 dredge closed during its descent or ascent, and therefore it is 

 quite within the limits of probabUity that sometimes fishes 

 were accidentally enclosed within the dredge, whilst it was 

 traversing the surface strata. And this has happened more 

 than once ; for it is quite certain that common surface fishes 

 like Sternoptyx and Astronesthes, never ranged to a depth 

 of 2500 fathoms. On the other hand, the majority of the 

 fishes obtained offer sufficient evidence from their own organ- 

 isation that they live on the bottom, and are unable to 

 support themselves in the water at a certain distance from 

 the bottom or surface ; and, consequently, that they actually 

 were obtained at the depth to which the dredge descended. 



As far as the observations go at present, no distinct 

 bathymetrical regions, which would be characterised by 

 peculiar forms, can be defined. The depths from 200 to 



