METAMORPHOSES. 21 



sacks, retained all the characters of the natatory larva. 

 According to Mr. King, the larva of Lepas throws off its 

 external shell five days after becoming attached. Whilst 

 the young Lepas is closely packed within the larva, the 

 capituliun, as known by the five valves, about equals in 

 length the peduncle. The peduncle occupies the anterior 

 half of the larva ; when fully stretched, it becomes nar- 

 rower and slightly longer than the capituliun ; the sepa- 

 ration between the capituliun and peduncle is almost 

 arbitrary in the mature animal, and corresponds with no 

 particular line in the larva. Even at this early period, 

 the muscles of the peduncle are quite distinct. No 

 vestige is preserved in the outer integument, of the sternal 

 and dorsal sutures of the larval carapace ; but in the 

 corium of the peduncle, three coloured marks which 

 occur near the eyes, and two little curled marks which 

 occur near the acoustic orifices of the larva, are all pre- 

 served for some time after maturity. The compound 

 eyes, as we have seen, are attached to apodemes, spring- 

 ing from the sternal surface of the larval carapace, and 

 are consequently cast off with it ■ whilst the young Cirri- 

 pede is packed within the larva, the outer integument of 

 its peduncle necessarily forms a deep transverse fold pass- 

 ing over the eyes and apodemes, and this, as we shall 

 presently see, plays an important part in the future 

 position of the animal. The antennas are not moulted 

 with the carapace, but left cemented to the surface of at- 

 tachment; their muscles are converted into sinewy fibres, 

 the corium after a short period is absorbed, and they are 

 then preserved in a functionless condition. No trace of 

 the two acoustic sacks can be perceived in the corium 

 of the young Cirripede, excepting the coloured marks 

 above alluded to. 



In the young capitulum, the five valves stand some 

 way apart from each other; they are elegant objects 

 under the microscope ; they are not calcified, but con- 

 sist exclusively of chitine; they are rather thick, com- 

 posed of an outer membrane lined by hexagonal prisms, 



