3 86 THE POPULAR SCIENCE MONTHLY. 



two, the " Tropical Pacific " and the " Antarctic " region, the last in- 

 cluding the Patagonian seas as well as those of New Zealand and Tas- 

 mania. The fishes of the second category (brackish water), owing to 

 the fact of their living in salt-water equally with fresh, and thus being 

 able to spread readily over the globe, can not help in any plan of par- 

 celing out the earth's surface into districts. The shore-fishes afford a 

 somewhat better definition, and of them five groups are formed, which 

 inhabit respectively the Arctic Ocean, the Northern Temperate Zone, 

 the Equatorial Zone, the Southern Temperate Zone, and the Antarctic 

 Ocean. The pelagic fishes seem to require separation, but as little can 

 be deduced from them as from the inhabitants of brackish waters, and 

 they insensibly mingle with the fishes of the deep sea. 



Thirty years ago no one had the audacity to believe that the abysses 

 of the ocean were tenanted with piscine life. Even animal life of any 

 sort had been supposed to be inrpossible at a greater depth than that 

 which has now been found to be but the portal of a new world of 

 beings. The discovery of what has since been proved to be deep-sea 

 forms of fishes began indeed long ago, but the abysmal nature of 

 their haunts was hardly suspected, and certainly not recognized till 

 much later, when the fact was established by Dr. Giinther, conjointly 

 with the late Mr. James Yate Johnson. On this subject Dr. Giinther 

 says : " The knowledge of the existence of deep-sea fishes is one of the 

 recent discoveries of ichthyology. It was only twenty years ago, that, 

 from the evidence afforded by the anatomical structure of a few sin- 

 gular fishes obtained in the North Atlantic, an opinion was expressed 

 that these fishes inhabited great depths of the ocean, and that their or- 

 ganization was specially adapted for living under the physical abyssal 

 conditions. These fishes agreed in the character of their connective 

 tissue, which was so extremely weak as to yield to, and to break under, 

 the slightest pressure, so that the greatest difficulty is experienced in 

 preserving their body in its continuity. Another singular circumstance 

 was, that some of the specimens were picked up floating on the surface 

 of the water, having met their death while engaged in swallowing or 

 digesting another fish not much inferior, or even superior, in size to 

 themselves. The first peculiarity was accounted for by the fact that, 

 if these fishes really inhabited the great depths supposed, their removal 

 from the enormous pressure under which they lived would be accom- 

 panied by such an expansion of the gases within their tissues as to 

 rupture them, and to cause a separation of the parts which had been 

 held together by the pressure. The second circumstance was explained 

 thus : a raptatorial fish, organized to live at a depth of between five 

 hundred and eight hundred fathoms, seizes another usually inhabiting 

 a depth of between three hundred and five hundred fathoms. In its 

 struggles to escape, the fish seized, nearly as large or strong as the 

 attacking fish, carries the latter out of its depth into a higher stratum, 

 where the diminished pressure causes such an expansion of gases as 



