Corals and coral islands.

BR YOZOANS.

105

In the Stylasteridae, the cyclosystems occupy usually stellate cells which stand out prominently along the branches, and
look much like the calicles of an Oculina (Figs. 2, 3, p. 69).
S. P. Sharples found the coral of M7. alcicornis to consist
of 97-46 per cent of carbonate of lime, 0-27 of phosphate of
lime, and 2-54 of water and organic matters. The Millepores
contribute largely to the material of coral reefs.

MILLEPORA ALCICORNIS, LINN.
The ancient corals of the Chaetetes family may be Hydrocorallinae, as suggested by Agassiz, but more probably were
Bryozoan.
III. BRYOZOANS.
The Bryozoans are very small animals, and look much like
Hydroids. Although belonging to the sub-kingdom of Mollusks, they are externally polyp-like, having a circle or ellipse of