358 THE INHABITANTS OF THK SEA. 
similar to the huge Chrysaora, from one of whose ova the 
primitive hydratube was produced. 
In a similar manner the Coryniade, a family of hydrozoic 
Various forms of Coryniade. 
a and b. Vorticlava humilis. ¢. Four polypites of Hydractinia echinata, growing on a piece of shell. 
d. Portion of Syncoryne Sarsit, with medusiform zodids (eg), budding from between the ten- 
tacles (+) of the polypite (0).— (All, except a, magnified.) 
polyps, which, unpossessed of the firm investment of the sertula- 
rians, are frequently found decking sea-weeds and stones with 
dense arborescent structures, give birth to detached medusi- 
form zooids. On the other hand, many medusid forms produce 
organisms directly resembling their parents, and many fixed 
Hydrozoa, such as the Sertularide, do not give birth to free- 
swimming medusoids, but to ciliated gemmules, which, escaping 
from the capsules in which they had been formed, soon evolve 
themselves into true polyps. A great part of this “ strange 
eventful history” is still enveloped in darkness, as the life of 
comparatively but few Hydrozoa has been thoroughly in- 
vestigated; so much is certain that future observations will 
bring many new interesting relationships to light, and add new 
links to the chain which binds together the various members of 
the hydrozoic class. 
Although the Ctenophora, thus named from the ciliated bands 
which constituteso obvious a feature in their physiognomy, closely 
resemble the Medusew by their gelatinous consistence and their 
mode of life, yet a more complex organisation assigns them the 
