382 SYDNEY J. HICKSON. 



although the zooid has to all appearance changed into a 

 medusa^ one or two of these large nematocysts remain. 



II. The Male Gonophores of Allopora and 



DiSTICHOPORA. 



1. Distich op or a. — The male gonophores of Distichopora 

 may be seen in clusters on the branches of the male stocks. 

 They are small whitish bodies lying in the ampullae of the 

 ccenosteum, and covered by a very thin semi-transparent wall 

 of lime and ccenosarcal canals. 



An examination of a series of sections through one of these 

 branches shows that the male gonophores are found only in 

 these superficial clusters (fig. 12). They are never found 

 deeply seated in the ccenosteum, nor in other places than those 

 indicated by external appearances. 



One, two, or even three gonophores, in different stages of 

 development, springing from a diverticulum of the coeno- 

 sarcal canal system, may occupy each ampulla. 



A ripe male gonophore (fig. l4<■^) is a spherical, oval, or 

 pear-shaped body, with an endodermal cell mass, representing 

 the trophodisc on the side turned towards the axis, and a 

 short conical or tubular seminal duct on the side turned 

 towards the periphery. The sheath of the gonophore seems 

 to be a simple layer of flattened ectoderm ; but I am per- 

 suaded, after the examination of a great many sections and 

 the study of the development, that two layers are represented, 

 the inner or endodermal layer being extremely attenuated 

 and devoid of nuclei. 



When a very young bud is examined with a high power 

 (figs. ISg, 14.^, 15), the rudiment of the spermarium may be 

 seen to be a homogeneous mass of protoplasm, containing a 

 number of large spherical nuclei. It occupies a position 

 apparently between the ectoderm and endoderm of the bud. 

 As the spermarium increases in size the endoderm becomes 

 cup-shaped in the bud, and the margins of the cup are pro- 

 duced into a verv thin sheath between the ectoderm and the 



