194 SYDNEY J. HICKSON. 



distinct germinal vesicle and spot. Each ampulla contains 

 invariably only one spadix and ovum." 



Moseley gives a detailed account of the female gonophore 

 of Cryptohelia pudica. In a late stage the trophodisc 

 is "complicated at its margin by subdivision of its lobes, 

 which form a network over one half of the surface of the 

 ovum, terminating in a fringe of numerous tentacula-like 

 lobes." 



From these descriptions of Moseley and ray own it seems 

 probable that the female gonophores of the various genera 

 of Stylasteridae are very similar in general structure to one 

 another. Moseley does not describe nor figure an inner en- 

 dodermal membrane covering the egg, but in other respects 

 his descriptions of the female gonophores of the three genera, 

 Errina, Pliobothrus, and Cryptohelia, agree with mine of Allo- 

 pora and Distichopora, The chief point of variation among 

 the different genera is probably the lobulation or branching of 

 the margins of the cup-shaped trophodisc. 



I prefer to retain the word trophodisc that I introduced in a 

 former paper to the word spadix used by Moseley for the cup- 

 shaped receptacle of the ovum. This structure cannot be con- 

 sidered to be strictly homologous with the spadix or manubrium 

 of the adelocodonic gonophore of the Hydromedusse. It seems 

 to me to be more probable that it is homologous with the 

 umbrella. 



IV. The Gonophores of the Hydrocorallin^e and 

 HydromedusjE compared. 



In the absence of a knowledge of the minute anatomy of 

 the gonophores of the Hydrocorallinae, the true position of 

 this group in the classification of the Hydrozoa has not yet 

 been very satisfactorily made out. 



The peculiar characteristics of the group, namely, the dimor- 

 phism of the polyps and the extensive skeleton of carbonate of 

 lime, have not been considered by naturalists to be of sufficient 



