588 I'lKX'KKDIXdtS OF THE NATIONAL MUSEUM. v..l. xwni. 



whicli iisiuilly point ohliciuely l)iick\\iir(l, and arc of peculiar shape. 

 Cylindrical at the basc^ for about onc-tifth of their entire Iciiti-th they 

 then flatten antero-posteriorly and broaden .slig-htly into the shape of 

 a spatula oi" pa})er cutter. 



They ar(> not seginented and not readily nioval)]e; they seem to be 

 used as a kind of l>alancing organ when tlu^ nauplii assume an upright 

 position in the water on coming to rest. 



The uniformity in the shape of these l)alancers as well as that of the 

 body of the nau})lii and the three pairs of appendages is good evi- 

 dence of th(^ close relationshii) of the genera here considered. 



If a female be captured with (^^^^ nearl}" or (piit(» matured it is an 

 easy matter to secure nauplii by keeping her over night in cool water. 

 But to rear the nauplii successfully is a very different mattiM- for many 

 reasons. 



In the hrst place they are extremely sensitive to even a slight rise in 

 temperature and of course can not be kept in an a([uarium of running 

 water, and as they advance toward the chalimus stage they require 

 freshly acM'ated water far more than in the nauplius stage, which it is 

 exceedingly difficult to supply properly. A great many different 

 methods have l)een tried, Init the best success thus far has been 

 ol)tained by keeping the larvw in floating aquaria or bags of cheese 

 cloth, innnersed in the ocean. The mouth of tlie ])ag is o})en and it is 

 floated at a sufficient height above the surface of the water to prevent 

 the washing out of the larva\ 



As the latter naturally swim at the surface, this insures just the 

 right temperature. And if they eat an3'thing prior to the metanauplius 

 stage, which is very douljtful, a})parently enough food gets in through 

 the meshes of the cheese cloth to keep them alive. In this way the 

 nauplii of two species of Callgus^ C luijxu' and ('. honlfo^ and one 

 species of L(']?eophtlu'lrui<^ L. edwitrdxi, have l)een carried through 

 several moults. 



But of coui'se when they rc^ach the stage at which they would ordi- 

 narily fasten upon some host, all artificial methods fail, and we nmst 

 dt^pend for further material upon a careful examination of the fish's 

 body. To achieve any success demands a knowledge of two things, 

 the particular host or hosts preferred by any given parasite and the 

 time of breeding. J>y securing a plentiful supply of the host just 

 after the i)arasite's eggs have hatched one may be reasonably sure of 

 finding some lar\ ;e attached to them. 



15ut ol)viously the securing of these early stages will require a very 

 minute examination of every part of the fish's body, since the larva 

 apparently fastens itscdf to the first place it happens upon, and may 

 show no indications whatever of a })reference for particular localities, 

 which later in lif(> l)ecomes very marked. EspiH'ially is this true of 

 such species as frecpient the mouth and gill cavity. C<(/i(/K.-> honito in 



