Note 8 — Chapter IX · DEVELOPMENTAL HISTORY OF ENTOMOSTRACA, CIRRIPEDES, AND RHIZOCEPHALA.

The roots of Sacculina purpurea (Fig. 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 (Fig. 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.