IV METAMORPHOSIS SI 
place; at this stage the body has the appearance shown in 
Fig. 51. The region of the head at the base of the antennae 
now becomes greatly swollen and elongated to form the peduncle 
Fie. 49. 
Nauplius larva of Lepas fascicularis, x 12. Aj, A», Ist and 2nd antennae ; 
B, brain; H&, eye; H, fronto-lateral horn ; J, mandible; S, stomach. (After 
Groom.) 
or stalk of the adult; the larval bivalve carapace is cast off 
and on the external surface of the mantle the calcifications begin 
which will give rise to the exoskeletal plates of the adult. This 
region is known as the “ capitulum ” of the adult, as opposed to the 
“peduncle.” The young Cirripede is now known as a pupa, and 
from this stage the adult form is reached by a gradual transition. 
VOL. IV G 
