^°!s(ti" ] PROCEEDINGS OF THE NATIONAL MUSEUM. 119 



eluded from corapetitio?i. There is the greatest variety of competitors, 

 the greatest variety of lish-food, and tiie greatest variety of conditions 

 to which adaptation is possible. The nnmber of species visiting any 

 single area is vastly greater in the tropics than in cold regions. 



A single drawing of the net on the shores of Cnba* will obtain more 

 dittereut kinds of fish tlnni can be fonnd on the coasts of Maitui in a 

 year. Cold, monotony, darkness, isolation, foul water; all these are 

 characters opposed to the formation of variety in fish-life. The absence 

 of these is a chief feature of life in the tropical waters. 



The life of the tropics, so far as the tishes are concerned, offers analo- 

 gies to the life of cities, viewed from the standpoint of human develop- 

 ment. In the same way, the other regions under consideration are, if 

 we may so speak, a sort of ichthyological backwoods. In the cities, in 

 general, the conditions of individual existence are most easy, but the 

 competition is most severe. The struggle for existence is not a strug- 

 gle with the forces and conditions of nature. It is not a struggle with 

 wild beasts, unbroken forests, or a stubboid soil, but a competition be- 

 tween man and man for the 0[)portnnity of living. 



It is in the cities where the influences which tend to the moderniza- 

 tion and concentration of the characters of the species, the inteusitica 

 tion of human powers and their adaptation to the various special con- 

 ditions go on most rapidly. That this intensification is not necessarily 

 progress either ])hysically or morally is aside from our present purpose. 



It is in the cities where those characters and qualities not directly 

 useful in the struggle for existence are first lost or atrophied. 



Conversely it is in the "backwoods," tin' region most distinct from 

 human conflicts, where primitive customs, antiquated ]>eculiarities, and 

 useless traits are longest and most persistently retained. The life of 

 the backwoods will be not less active and vigorous, but it will lack 

 specialization. 



It is not well to push this analogy too far, but we may perhaps find 

 in it a suggestion as to the development of the eels. In every city there 

 is a class which partikes in no degree of the general line of devel- 

 opment. Its members are specialized in a wholly difl'erent way, thereby 

 taking to themselves afield which the others have abandoned, and mak- 

 ing up m low cunning wiiat they lack in strength and intelligence. 



Thus among the fishes we have in the regions of closest competition 

 a degenerate and non-ichthyized form, lurking in holes among rocks 

 and creeping in the sand, thieves and scavengers among fishes. 



The eels till a place which would otherwise be left unfilled. In their 

 way, they are perfectly adapted to the lives they lead. A multiplicity 

 of vertebral joints is useless to the typical fish, but to the eel strength 

 and suppleness are everything, and no armature of fin or scale or bone 

 so desirable as its power of escaping through the smallest opening. 



* lu 1884 a single haul of a net in a shallow bay on Key West brought in seventy- 

 five species. A week's work about Martha's Vineyard yielded but forty-eight kinds. 



