RER 
(Agassiz.) 
THREE CRUISES OF THE “BLAKE.” 
Fig. 441. — Animal of Millepora. 2. 
HYDROCORALLINZE. 
To the hydroids we should add the account of the Hydro- 
coralline, which until recently were supposed to be true corals. 
Professor Agassiz, however, observed the animal of Millepora, 
and traced its acalephian affinity. 
The polyps of Millepora are most 
difficult to observe (Fig. 441), 
not only on account of their small 
size, but also from their extreme 
sensitiveness to contaet with air. 
Agassiz's observations have been 
confirmed by several investigators, 
especially by Moseley, who has 
greatly increased our knowledge 
of the group, and has in addition 
shown that other families of cor- 
als, the Stylasteride and Helo- 
porid:ze, belong with the Millepo- 
ride to a natural group for which he has proposed the name 
Hydrocoralline. They are all characterized by having reproduc- 
tive, prehensile, and. digestive zoids composing the community 
(Fig. 442), reminding us thus somewhat of the siphonophores. 
Fig. 442. — Millepora nodosa, Dactylozoid Gastrozoid ; magnified. (Moseley. ) 
The best known member of the group is the shallow-water 
Millepora (Fig. 443), which is represented in deep water in the 
Caribbean and Florida districts by P/iobothrus symmetricus: 
