ANIMAL PARAS1TP:S 177 



althoLig-h of different species. The tawny owl 

 presents l^y way of contrast ( Lig. i 16), a parasite 

 that is not slender ])odied, but exhibits an alder- 

 manic outline SLiggestive ot unearned increment. 



Fish also ha\"e their personal attendants, and 

 one ot these, taken from the fresh-water pike, is 

 shown in Pig. 117 ; this species is also found on 

 carp, and perhaps more often on the small but 

 mtercsting stickleback. It may seem to be upside 

 tlown as represcntetl in our illustration, on com- 

 paring it with the other pictures, but its position is 

 correct. I he legs are attached to the posterior 

 part ot its anatoni)', and constitute paddles by 

 means t^t which the creature can change its 

 host, and depart to pav its attentions to another 

 fish. The two dark s[)ots seen in the forepart 

 of the creature represent the first pair ot legs, 

 which have been converted into suckers, by nieans 

 of which it retains hold of its slippery host. 

 Perhaps, as is the case of the slender parasite 

 of the pigeon, we do this fish-dweller an in- 

 justice by including him with those parasites 

 that live more or less at the expense of their hosts. 

 fOr there is good reason to l)elie\'e that he is not 

 a torment to his host, but rather a usetul A'alet. 

 In all probability it derives its n(.)urishment trom 

 the superrtuous products secreted by the skin ot 

 the fish. And when he has satisf ictorily arranged 



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