126 THE FAUNA OF THE DEEP SEA 



Another point that should be considered in 

 coming to any conclusion on the supposed habitat of 

 such forms, is the similarity or dissimilarity of widely 

 distributed species. 



I have had occasion to point out in a previous 

 chapter the general similarity of the abysmal fauna 

 all over the world, a very striking phenomenon, com- 

 mented on by almost every naturalist who has had 

 a wide experience of this kind of investigation. 



Among the Amphipoda we have a very striking 

 example of this. The species Orcliomene musculosus 

 was taken by the ' Challenger ' off the southern part of 

 Japan at a depth of 2,425 fathoms, the bottom being 

 red clay and the temperature 35-5° Fahr. The 

 species Orcliomene ahyssorum was taken off the east 

 coast of Buenos Ayres at a depth of 1,900 fathoms, 

 the bottom being blue mud and the temperature 

 33-1° Fahr. To the description of this last-named 

 species Mr. Stebbing adds, ' had this species been 

 taken within reesonable distance of 0. musculosus ^ 

 the resemblance is so great that one might have been 

 tempted to disregard the points of difference as due 

 to some other cause than difference of species.' 



Such a striking similarity between two species 

 living so far apart from one another may, when we 



