28 ON THE AFFINITIES OF THE FAMILY OF THE MEDUSA 



72. Perhaps the view that I have taken will be more clear if I 

 throw it into a tabular form, placing opposite one another those organs 

 in the different families, for the homologies of which there is, I think, 

 sufficient evidence, thus : — 



Stomachs identical in Structure tliroiigliout. 

 Medusce. Physophoridce. Diphyda:. Sertularida: HydnT. 



Disc Natatorial organ . . . Natatorial organ. 



Canals Canals of natatorial 



organ Canals of natator- 

 ial organ. 

 Common cavity... "j 



Canals of branches ICommon tube Sacculiisandcom- 



[Rliiz.) J mon tube Cavity of stem. 



Bract Polype-cell. 



Tentacles, i Thickened edge of 



stomach Oval tentacles. 



2 Prehensile organs Clavate organs ...Tentacles (?). 



(•Generative sac Generative organ. Generative organ. 



Generative organs-. Natatorial organ of 



I generative sac Natatorial organs 



(Coryne). 

 IWarginal vesicle ? ? ? 



73. It appears then that these five families are by no means so 

 distinct as has hitherto been supposed, but that they are members of 

 one great group, organized upon one simple and uniform plan, and 

 even in their most complex and aberrant forms, reducible to the same 

 type. And I may add, finally, that on this the"ory it is by no means 

 difficult to account for the remarkable forms presented by the Medusae 

 in their young state. The Medusa are the most perfect, the most 

 individualised animals of the series, and it is only in accordance with 

 what very generally obtains in the animal kingdom if in their early 

 condition they approximate towards the simplest forms of the group 

 to which they belong. 



74. 1 have purposely avoided all mention of the Beroida; in the 

 course of the present paper, although they have man}' remarkable 

 resemblances to the animals of which it treats : still such observations 

 as I have been enabled to make upon them have led me to the belief, 

 that they do not so much form a part of the present group as a link 

 between it and the Anthozoic Polypes. But I hope to return to this 

 point upon some future occasion. 



Sydney, April 24th, 1848. 



*^* Since the above was written I have had an opportunity (by 

 the kindness of W. MacLeay, Esq., to whose advice I am much 



