THE CIRRIPEDIA. 477 



sea-weed and other objects, are in reality the altered large antennae 

 of the larva of the first stage ; but the smaller antennae have wasted 

 away. The eye has commenced becoming double, but is not as 

 yet compound in structure. The mouth is still in the form of a 

 proboscis, and does not differ much from its former condition. 

 But no jaws or mouth-pieces are present. The legs are still in 

 three pairs, the mouth bears the same relation to them as before, 

 and the abdomen has become short. 



Considerable increase in size takes place during the development 

 of the Cirripede up to the time when it is about to enter the third 

 larval state, which, from its having some peculiarities, that will 

 be noticed hereafter, is more or less correctly termed the pupal 

 condition. 



On comparing the larva of the second stage and the pupa, no 

 very great external changes can be discovered ; but the great 

 antennae have come out of their surrounding cases, the carapace 

 has extended so as to enclose the whole body, the eyes have 

 become further apart, and three other pairs of legs have been 

 developed behind the others. Moreover, a small abdomen has 

 become slightly separated from the thorax. The mouth, formerly 

 a proboscis, and active enough in swallowing and seizing, is now 

 closed and functionless ; but its position is marked by a sort of lip, 

 the old shrivelled ceosphagus, and the commencing jaws and new 

 gullet. This mouthless pupa can swim rapidly, but it does not 

 appear to have much, if any, power of steering itself, and it 

 differs in these peculiarities from the larva, for that could swim 

 where it chose, and with considerable energy. The pupa of one 

 species of Lcpas can walk tolerably over sea-weed with the aid 

 of its large antennae ; and these are formed of four segments, those 

 nearest the body supporting the eyes. The position of the cement 

 tubes with respect to the antennae of the perfect Balaniis has 

 been already noticed. They may be traced in the pupa to end in 

 a third and disc-shaped segment, which is used as a climbing 

 structure. The cement constantly exudes from the outside of the 

 disc, and finally it causes the antennae to adhere permanently. 



Whilst the pupa remains a free swimmer, the eyes, the position 

 of which to the antennae has been noticed above, are included within 

 the carapace or shell, but they are within the skin lining it. But 



