478 
TRANSFORMATIONS OF INSECTS. 
when the pupa adheres by its antennae to its future resting-place, 
the skin is absorbed, and the new one does not include these organs 
of vision. It thus happens that they are very visible through the 
transparent shell before the last metamorphosis, which occurs at 
the close of the pupal condition. Soon, however, these eyes lose 
their powers ; their nerve becomes absorbed, and after a while the 
carapace and all are moulted and cast off. 
“The eyes of Cirripedes ,” writes Mr. Darwin, “certainly undergo 
a remarkable series of changes. In the first larva there is a single 
eye, perhaps formed by the confluence of two, occupying the 
normal position in the front of the head ; in the second stage the 
eye has become double, but the two are as yet simple — they are 
now situated posteriorly to the second pair of antennae; in the third 
or pupal stage, they remain in the same situation, but have become 
compound, of great size, and are attached to the bases of the 
antennae ; in the mature or fourth stage, they have moved away 
posteriorly, and again have become simple, of minute size, and are 
either confluent, as in Lepas , or tolerably perfect, as in Balanus 
It must not be supposed that the eye of the mature Cirripede is 
metamorphosed from the eye of the pupa, for such is not the case, 
the new eyes and the old eyes are formed some way apart, and 
frequently both can be seen within the pupa at the same time. 
The future mature young Cirripede is gradually perfected within 
the pupa. The mouth is formed under the rudimentary and useless 
mouth of the pupa, and a new oesophagus is elaborated around the 
old one. After the casting of the outer parts of the pupa, many 
old markings are retained by the perfect creature, and it is 
observed that the extremities of the cirri, which are so important 
in the mature barnacle, are formed within the old legs ; moreover, 
it is evident that the body (thorax) of the young Cirripede is not 
formed within that of the pupa, but within a portion anterior or in 
front of it. The position of the body becomes changed in conse- 
quence, the alimentary canal is shortened to half its former length, 
and the space which formerly existed between the mouth and the 
first pair of legs is lost by coalescence. When the due time for the 
act of metamorphosis has arrived, the carapace of the pupa splits 
along the back, and is cast off, together with some of the segments 
of the antennae of the eyes and some other structures. The three 
