386 SYDNEY J. HICKSON. 



good state of preservation. The " inner sac " of the gono- 

 phore that he mentions and figures is most probably the same 

 as the inner endodermic lining that I have described in both 

 Allopora and Distichopora. It would be certainly very 

 remarkable if this membrane is not attached to the endoderm 

 of the pedicle in Astylus, but this point can only be deter- 

 mined with accuracy by the examination of a continuous 

 series of sections. 



The male gonophores of Cryptohelia pudica seem to be 

 similar to those of Astylus. 



III. The Female Gonophores or Distichopora. 



The position of the female gonophores of Distichopora can 

 be readily seen on the female stocks by the prominent swell- 

 ings on the surface of the corallum. They are usually situated 

 on only one side of the thicker branches, but occasionally 

 there may be found in addition a small cluster on the opposite 

 side. 



A section through one of these clusters shows the eggs and 

 embryos in many stages of development, from the minute im- 

 mature yolkless eggs in the coeuosarcal canals to well-advanced 

 planulse (fig. 21). 



The mature ova (fig. 2S,ovu7n) are 0*3 to 0*4 mm. in diameter, 

 and contain a large number of spherical yolk-globules. The 

 large germinal vesicle is situated close to the peripheral border 

 of the egg, and is surrounded by a number of yolk-globules 

 much smaller in size than those of the other part of the egg. 

 The eggs rest in the cup-shaped trophodisc (cf. Allopora, 

 Hickson, 7), and is covered by a thin coat of ectoderm and 

 endoderm. The trophodisc is similar to that of the female 

 gonophores of Allopora, but not so complicated in its foldings. 

 In transverse section it exhibits twelve pouches at its margin 

 (fig. 24). In vertical section it is simple (fig. 23) ; the inner 

 and outer pliets that I have described in Allopora are not found 

 in this genus. 



When fertilisation has taken place the germinal vesicle loses 



