370 
CLASS CRUSTACEA. 
first two of the swimming feet, are the only ones which are 
developed and free ; the following are, as it were, swathed up, 
and fixed on the abdomen. The heart, the proboscis, and 
the ramifications of the appendages of the stomach, are all 
distinct. When the first moulting, which is performed by 
means of a rupture of the lower surface, has taken place, the 
oars disappear, and all the swimming feet are to be seen. 
Three days after comes the second moulting, which produces 
no important change. But at the third, which takes place 
two days after, we commence to perceive, towards the 
middle of the two anterior feet, the rudiments of the cup- 
pers. On the fourth moulting, which likewise takes place 
at the end of two days, these same feet are finally trans- 
formed into regular cupping-feet, preserving, however, the 
terminal hook. At the end of six days comes a fresh change 
of skin, and the appearance of the genital organs of either 
sex ; but another moulting, which is delayed for six days 
longer, is necessary to enable these animals to unite and mul- 
tiply. Thus the duration of their state of infancy, or of their 
metamorphoses, is five and twenty days. As yet, however, 
they have arrived to but one-half of their proper size. For 
this, some other moultings, which take place every six or 
seven days, are necessary. Jurine has ascertained that the 
females cannot become mothers without the intervention of 
the males. Those which he had isolated, perished of a dis- 
ease, which was indicated by the appearance of several brown 
globules, disposed in a semi-circle towards the posterior part 
of the hood, and which are formed, as it would seem, in 
the parenchyma, since they are not destroyed by the 
moultings. 
The only known species of this genus, Argule foliacee , 
(Jurine fils., Ann. du Mus. dTIist., Nat., vii. xxvi., Monocii- 
lus foliaceus, Linn., Argidas delphinus , et argulus char on. } 
Mull.,Entom.,^fr^w/ws delphinus , Herm. fils., Mem. Apter.v. 3. 
