488 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvm. 



Many sp(»ci«'s show in tendonc^y to con<»Teoate in certain places to the 

 ahiiost (Mitir(» exchision of tlie vest of th(> Hsh's body, as in the case of 

 (UdhjiiK hoiitio and J.cpi (>2)hfli('/i'ns jn'cioi'dhx. 



Whih> many of the species stick to one particuhir host there are 

 others which change hosts from tinu^ to time and which are al)le like 

 tiie ^Vryuli(hx» to live temporarily u])oti ahnost any fish that may he 

 avaihil)le. ('<il!(jns luijui.r easily tak(\s th(> lead in this, having been 

 found upon 1 wcnty-tive oi' thirty ditl'erent lish. A few of these like 

 the flounder and cod are regular hosts, and an examination of a very 

 few tish is almost cci'tain to rexcal the presence of this parasite. 

 At the light seasons also the ehalinuis stages of development may he 

 found attached to the fins and scales of the same fish. But for the 

 other hosts there is often a record of" only a single specimen which was 

 evidently a straggler and took that particular tish until it could find 

 something better. 



I<T)()I). 



These paiasites feed upon the blood of their hosts which they obtain 

 in the same manner as did the Argulids l)y bun-owing under the scales 

 or piercing the skin on the tins with their maxillipeds and proboscis. 

 This blood, filling the central digestive system, may often be seen as a 

 dark streak through the body, and is sometimes very })rominenf in 

 transparent specimcMis. 



\\'lien taken fi'om the fish those specimens usually live the longest 

 which ha\e the ujost blood in them; th(^ latter seems to digest slowdy 

 and may often be s(hmi for several davs in the intestine. 



Many autlK)rs write that these parasit(\s. or some of them at least, 

 feed upon the nuicus of the fish's body and that no blood has ever been 

 found in their stomachs. 



This statement seems to rest entirely upon the fact that no red color 

 can be seen in their digestive organs. A. Scott sa3's of Lepeophfhetnoi, 

 pectordJti'i, '" wdien taken directly from the living tish and placed under 

 the microscope it rarely shows even the faintest trace of red coloi'ing 

 matter in the alimentary canal.'' 



But the same author concludes on the next page that this species 

 feeds to some extent on blood, and a little later he adds "they do not 

 hesitate to eat th(Mr comrades wdien these become feeble." Fjr animals 

 which will do this nuu'us must l)e a rather tame and inadeciuate food. 



It is dillicult to d(>ternune wdiat the food really is, but there are s(>v- 

 eral considerations which will help us to foi-m a rational judgment in 

 the matter. In the first place, it makes a difference what part of the 

 fish's body the parasite is fak(Mi from, wheflnn' if shows an}' red in the 

 digesfi\-e organs or not. 



If taken from the gill caxity the red is lunii'ly always })r()min(mt, 

 while it seldom apjx^ai's in lhos(^ indi\'iduals taken from th(^ outside of 

 the body. Some s])ecies are always found in the gill cavity and the}" 



