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. d'Hist., Nat., vii. xxvi.,iHoMOcv<- 

 his foliaceus, Linn., Argnlus delphinus, et argulus charon., 

 Mull.,Entom.,/ir/7?///^s delphinua, Herm. fils., Mem. Apter.v, 3, 



