158 



ZOOLOGY 



closely resembling the true cup-corals belonging to the Actinozoa 

 {vide infra). But in the case of Stylaster each " cup " is 

 the locus, not of one, but of several zooids-— a polype projecting 

 from its centre, and a dactylozooid from each of the compartments 

 of its peripheral portion. A calcareous projection, the style, the 

 presence of which is the origin of the generic name, rises up from 

 the tabula at the bottom of each pore. 



The gonophores in most species of Millepora are developed in 

 certain of the pores in dilatations or ampulla ; in one species at 



end ect 



Fig. 117. — Millepora. Diagrammatic view of a portion of the living animal, partly from the 

 surface, partly in vertical section. In the sectional part the ectoderm is dotted, the endoderm 

 striated, and the skeleton black, ect. ectoderm ; end. endoderm ; d.p. dactylopore ; D.Z. 

 dactylozooid ; g.p. gastropore ; mth. mouth ; P. polype ; t. tentacle. (Altered from Moseley.) 



the apices of the dactylozooids. They are medusae, but never 

 have the complete medusa-form, being devoid of velum, mouth, 

 radial canals and tentacles. Both male and female medusoe 

 become free, but the period of free existence is very 

 short. 



In Stylaster the medusoid character is much more completely 

 lost, and the gonophores are more of the nature of sporosacs or 



