* (* The roots of Sacculina purpurea (Figure 60) which is
parasitic upon a small Hermit Crab, are made use of by two parasitic
Isopods, namely a Bopyrus and the before mentioned Cryptoniscus
planarioides (Figure 42). These take up their abode beneath the
Sacculina and cause it to die away by intercepting the nourishment
conveyed by the roots; the roots, however, continue to grow, even
without the Sacculina, and frequently attain an extraordinary extension,
especially when a Bopyrus obtains its nourishment from them.)
(FIGURE 59. Young of Peltogaster socialis on the abdomen of a small
Hermit Crab; in one of them the fasciculately ramified roots in the
liver of the Crab are shown. Animal and roots deep yellow.
FIGURE 60. Young Sacculina purpurea with its roots; the animal
purple-red, the roots dark grass-green. Magnified 5 diam.)
Out of several Cirripedes, which are anomalous both in structure and
development, Cryptophialus minutus must be mentioned here; Darwin found
it in great quantities together in the shell of Concholepas peruviana on
the Chonos Islands. The egg, which is at first elliptical, soon,
according to Darwin, becomes broader at the anterior extremity, and
acquires three club-shaped horns, one at each anterior angle and one
behind; no internal parts can as yet be detected. Subsequently the
posterior horn disappears, and the adherent feet may be recognised
within the anterior ones.
Pages:
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102