388 SYDNEY J. HICKSON. 



in Errina the ampullse project more and more above the surface 

 as development proceeds, 



''The spadix in Errina labiata is at first cup-shaped, the 

 walls of the cup being composed of a very thick layer of endo- 

 derm. The cavity of the cup is directed towards the surface of 

 the coral, and within it rests the single large ovum with its 

 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, ter- 

 minating in a fringe of numerous tentacula-like lobes." 



From these descriptions of Moseley and my own it seems 

 probable that the female gonophores of the various genera of 

 Stylasteridse are very similar in general structure to one 

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

 dermal 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 AUo- 

 pora and Distichopora. The chief point of variation among 

 the diflFerent 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 Hydromedusee. It seems 

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

 umbrella. 



IV. The Gonophores of the HydrocoralliNjE and 



HYDROMEDUSiE 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. 



