192 SYDNEY J. HICKSON. 



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 of 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 coenosarcal canals to well-advanced 

 planulse (fig. 21). 



The mature ova (fig. 23, ovum) 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 egg rests in the cup-shaped trophodisc (cf Allo- 

 pora, 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 

 its sharp outline, and remarkable changes occur in the shape 

 and arrangement of the yolk-globules. My observations are 

 not yet complete of the early stages of the development, but I 

 hope to be able to publish shortly a separate memoir, giving 

 a full account of the development of this form up to the stage 

 when the larva escapes from the ampulla. 



