276 ZOOPHYTES. 



tures ; another with fifty, a third with only ten. This is a subject which 

 has not yet received sufficient notice ; but it merits much attention. 



From this fact it results, that the variety of the polyparia — the habi- 

 tations of the zoophytical tribes are very numerous, while among the tribes 

 themselves, the varieties are apparently very few. 



We might be thence led to enquire whether it is the identical hydra 

 that is so widely dispersed amidst different formations, whether each diffe- 

 rent polyparium is not occupied by a distinct hydra, whereof the charac- 

 teristics, though obscure and indistinct, may be recognised by acute 

 observation. 



In our present state of knowledge, the variety of hydra; brought under 

 the description of British Zoophytes, even with the latitude assumed in 

 these volumes, is extremely limited. 



The Order of Zoophytes we have seen to be divided into four principal 

 sections in scientific treatises. I. The Hydraoid, comprehending Tubularia 

 and Sertularia. II. Helianthoid, comprehending the Actinia. III. The 

 Asteroid, comprehending Virgularia and Pennatula. IV. The Ascidian, 

 comprehending the Flustra and Cristatella. 



The hydra of each of these bears a distinct character. There is some 

 alliance between the animals of the first and second section. 



At present only the first three sections are deemed real zoophytes. 



The exact place of the Coryna squamata, and of the Pedicellina, is 

 somewhat questionable : that of the Coryna glandulosa is much more ob- 

 scure. 



The anatomy of the Hydra proper is scarcely farther explained or 

 understood than as discovered by simple inspection. Its nearest kindred 

 are probably the hydra of the Coryna squamata, and that of the Sertularian 

 Zoophytes : for it is scarcely logical to include an animal, though of inti- 

 mate resemblance, while in an acknowledged state of transition, such as 

 the Hydra tuba of the sea. 



The nature and the functions of the simple hydra are apparently more 

 obvious than those of the compound zoophyte. We discover the origin, 

 food, and the increment of individuals of the former more readily than 

 we see of the others. 



