234 Proceedings of the 



generation of Steenstrup, in which the parent is a zoophyte, 

 the child an acaleph, the grandchild a polyp again, and so on 

 in endless succession ; but as a new phase in the continued 

 development of the Zoophyte, in which the humble, fixed, and 

 thread-like polypary attains, as it were, a higher life of beauty 

 and motion, and an organization adapted to its changed exist- 

 ence. 



14. At our last meeting, I described to the Society that, in 

 the case of Hydractinia (a Zoophyte intermediate in its form 

 and structure between the true Zoophyte and the Acaleph) we 

 had a polypary consisting of a fleshy expansion permeated by 

 a net-work of tubes, and furnished with organs of reproduction, 

 digestion, and prehension, in the form of reproductive, alimen- 

 tary, and tentacular polyps. A homologous structure obtains 

 in the Acaleph now under our notice. Instead of a fiat ex- 

 panded polypary, we have that body bell-shaped, and repre- 

 sented by the umbrella, the sub-umbrella, and the lateral 

 canals. In the peduncle, we have a single alimentary polyp. 

 While the long tentacles, with their bulbs, form the homo- 

 logues of the tentacular polyps of Hydractinia. 



It is not, perhaps, incorrect to consider, with Allman, the ova- 

 ries and spermaries of Cordylophora, or those of Clava or Hy- 

 dractinia, as sexual polyps ; but, as to the naked-eyed Acalephs, 

 produced by gemmation from various hydroid Zoophytes, a 

 knowledge of the anatomy of Hydractinia teaches us that they 

 are something more. They are independent polyparies, hav- 

 ing polyps endowed with various functions ; some species of 

 them possessing, indeed, differentiated organs of sight and 

 hearing, and being capable, like Hydractinia, of producing 

 other polyparies, similar to themselves, by gemmation. 



In fig. 11 I have given an ideal sketch of Hydractinia as a 

 Gymnopthalmatous Medusa, and at fig. 12, having its organs 

 indicated by the same letters, a sketch of an ideal Acaleph or 

 free-swimming polypary, and I have furnished this last with 

 the alimentary polyp of Lizzia (a), the reproductive polyps of 

 Thaumantias (b), the tentacular polyps of Sarsia (c), with their 

 eye-specks, and the auditory capsules containing otolithes com- 

 mon to the Campanularian and many other Acalephs. Such 

 an animal would be endowed with the power and special appa- 



