British Protozoa and Zoophytes. 129 



of different function combined, each exercising its separate func- 

 tion, alimentative or reproductive ; that an organ composed of a 

 single subelement (a generative one) having only one function 

 cannot be homologous with one composed of two subelements 

 (peduncle of Sarsid) each having its distinct function, or with an 

 organ of sLxteen subelements (peduncle of Buugainvillea), eight 

 of which are alimentary and eight reproductive. I would there- 

 fore now state — 



That the simple generative sac of Coryne is homologous with 

 the reproductive subelement or single generative sac as it exists 

 on the lateral canal of Stomobrachium. 



That the peduncle-like sac of Eudendrium confertum is ho- 

 mologous with the reproductive subelement in the peduncle of 

 Sarsia — not with the whole peduncle. 



That where the generative sac evidently consists of many sub- 

 elements, as in Tubularia laryna; and Sertularia fallax (evidenced 

 by the four summit-lips or lobes, the symmetrical character of 

 each of which indicates it to be composed of two subelements), 

 it is homologous with the reproductive subelements in the octo- 

 partite peduncle of Bougainvillea, or, rather, with the eight 

 coalescing reproductive subelements of Eleutheria. 



I consider that a four-lobed or branched state of the placenta 

 or spadix indicates a multipartite constitution of the generative 

 sac, and not a rudimentaiy medusoid form of that organ ; for 

 we have, in the fixed female medusoid of Laomedea Loveni, a 

 four-lobed condition of the placenta in the peduncle-like ovisac, 

 with the existence of a well-differentiated subumbrella and 

 lateral and circular canals. 



My space will not allow me to illustrate the homological rela- 

 tions which exist between the polypary (or coenosarc) and the 

 polypidom, on the one hand, and the subumbrella and umbrella 

 on the other. This must be reserved for a future occasion, 

 when I hope to fill up the gaps in this rough and incomplete 

 sketch of some of the morphological relations of the Hydroidae 

 and their Medusse. 



Atracti/lis palliata, n. sp. PI. IV. fig. 6. 



Polypidom creeping, closely reticulate. Polyps fusiform, shortly 

 stalked, minute, white, with eight alternating tentacles ; body 

 of polyp clothed with a thick layer of ' colletoderm.' Free 

 medusoids springing from meshes of polypary, with four- 

 lipped peduncle ; four lateral canals ; two long marginal ten- 

 tacles and two tentacular tubercles alternately placed. 



This zoophyte was found on a shell inhabited by Pogurtis 

 Bernhardus, at Granton. When first observed, its closely-set 

 and dense white polyps, surrounded by their gelatinous envelopes, 



Ann. &; Mag. N. Hist, Ser. 3. Vol. viii. 9 



