56 Coelenterata. 



C. Hydrocorallia. 



Hickson & England describe from the Indian Ocean Stylaster 3, Allopora 1 

 (the first record for the Indian Ocean), Distichopora 2 (1 n.), Sporadopora 1 n. 

 (which shows affinities with D.), Cryptohelia 1, Conopora 2 (In.) and Spini- 

 pora 1. In a colony of D. violacea from Farquhar Atoll male and female sexual 

 cells are present in the same ampulla. Tabulae are commonly present in the 

 gastropores , especially the older ones , of D. profimda n. , they also occur in 

 the gastropores of violacea, and in both gastropores and dactylopores of Spini- 

 pora. D. prof, is the only species found in deep water (120-150 fms.) in the 

 Indian and Pacific Oceans. The dactylozooids of all Stylasterina (Pliobothrus 

 only was not examined) have solid endoderm. 



Mangan states that, in Millepora, the zooxanthellse pass from the rnanu- 

 brium into the ovum, sometimes prior to the liberation of the medusae. The 

 ova grow at the expense of their sister cells, the last of which are incorporated 

 about the time of liberation of the medusa. The cytoplasm of the ovum, at 

 first compact, becomes continuous with the central mesh-work of the manubrium, 

 and later vacuolated, as if part of the manubrium with its zooxanthellse had 

 been drawn in. In free medusae the ova are more vacuolated and have more 

 zooxanthellse, and the manubrium is greatly reduced. The zooxanthellse are 

 normal and undergo division. Two free male medusse were obtained from 

 Jamaica; the manubrium is without zooxanthellee. The oocyte is apparently 

 a plasmodium resulting from the fusion of several oogonia but the nucleus of the 

 oocyte alone persists. A nucleolus is at first present but soon disappears; a 

 chromatin reticulum is at first present, then disappears, but later reappears as 

 minute granules on the achromatic reticulum. In ova ready for discharge the 

 nucleus migrates to the periphery, loses its membrane and ejects chromatin 

 into the cytoplasm. One ovum snowed the first division of the cleavage- 

 nucleus and in another several nuclear divisions had taken place but the egg 

 had not yet segmented. 



