40 THE WORLD BENEATH THE WAVES 



such fishes and mollusks there are several species that 

 have the eyes reduced to hidden and useless rudiments, 

 and numerous species that have eyes of a most degener- 

 ate kind ; and among such crustaceans there is quite 

 a large number of species in which, though the eye- 

 stalks that their shallow-water relatives possess may 

 be present, the eyes show all degrees of degeneracy, 

 from grave imperfection to complete absence. 



But, unfortunately for a clear and concise account 

 of this matter, it is impossible to decide, with the 

 majority of animals brought to light by the deep-sea 

 dredge, whether they did or did not come from the 

 very bottom. Most fishes, many mollusks (especially 

 those related to the squid and octopus), and a large 

 number of Crustacea (those, namely, after the prawn 

 and lobster kind), are active swimmers, who, though 

 they may at times descend to the ''dark, unfathom'd 

 caves of Ocean," may at other times ascend to regions 

 where there is some little daylight. These we shall 

 not expect to have degenerate eyes ; on the contrary, 

 knowing what we do of certain land animals (such as 

 owls and night-jars, and certain fruit-bats, rats, cats, and 

 lizards) that come out only at night or in twilight, we 

 may rather expect them to have particularly keen vision 

 and large eyes for the better appreciation of such poor 

 light as does exist. And of this expectation we find, 

 in fact, much justification. Among those Crustacea, 

 mollusks, and fishes, which, though we dredge them 



