276 ZOOLOGY. 
concealing the rudimentary antennez, and the feet grow 
smaller, and eventually the barnacle-shape is attained. The 
Fig. 228.—Pupa of Lepas, much en- 
larged.—After Darwin, 
Fig. 227.—Nauplius of Balanus bal- 
anoides, much enlarged. 
common barnacle (Balanus balanoides) attains its full size, 
after becoming fixed, in one season, 7. ¢., between the first of 
April and November. 
Still lower than the genu- 
ine barnacles are the root-bar- 
nacles or Rhizocephala, repre- 
sented by Peltogaster (Fig. 
229) and Sacculina (Fig. 230), 
in which the young is a more 
simple Nauplius form, like 
the young of the Hntomostra- 
ca, while the adult is a sim- 
ple sac, with a ganglion, but 
no digestive organs. From 
the feet of the young grow 
out, after the animal becomes 
sessile, long root-like fila- 
ments, which ramify in the 
body of the crab, to which 
inese animals are firmly an- 
chored. We can conceive of larged 14 times, beneath the larva or Nau- 
no lower, more degraded Crus- Hines.-rom Beam’ Thisdebens 
tacean than these root-barna- 
cles, the only signs of life being the powerful contractions 
of the roots and an alternate expansion and contraction of 
aed — Peltogaster curvatus, en- 
e 
