BRYOZOANS. 105 
In the Stylasteride, the cyclosystems occupy usually stel- 
late cells which stand out prominently along the branches, and 
look much like the calicles of an Oculina (Figs. 2, 3, p. 69). 
8. P. Sharples found the coral of M. 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 Cheetetes family may be Hydro- 
coralline, as suggested by Agassiz, but more probably were 
Bryozoan. 
Ill. BRYOZOANS. 
The Bryozoans are very small animals, and look much like 
Hydroids. Although belonging to the sub-kingdom of Mol- 
lusks, they are externally polyp-like, having a circle or ellipse of 
