62 ACALEPIIS IN GENERAL. Part I. 



foiuplicatioii of strurtiur.' wliicli (k'tcrmiiK's the orders iu a class, but one of plan, 

 which stands even aJjove the consideration upon which classes are founded, and 

 determines the four great branches into which the whole animal kingdom is 

 divided. As to the Coral stocks lbrme(l l)y Bryozoa, they vary greatly, being 

 calcareous in some, as in P]st'hara ; horny iu others, as for instance in Acha- 

 marchis; and in others again, as in Ilalcyonidium or Holodactylus, altogether gela- 

 tinous. Moreover, these Bryozoan Coral stocl\s never exhilut in the cells occupied 

 by the animals, those radiating lanielhe so characteristic of the Coral stocks of the 

 Actinoids. On the contrary, these cells, into which the animals may withdraw 

 and conceal themselves entirely, are pertectly smooth, and the opening through 

 which the animal is protruded presents unifonnly a transverse, oblong, or crescent> 

 shaped aperture, similar to the gaping opening between the valves of a Lingula, 

 or the half-open shells of any other Brachiopod, with which they are much more 

 closely allied than would at fu-st appear. These cells are external, and do not form 

 a part of the body-wall of the aninuil, as do the radiating pits of the Actinoids. 

 The so-called arms of the Brachiopods are truly homologous to the marginal fringes 

 of the Bryozoa, betAveen the branches of which the mouth is placed in both. It 

 is therefore evident, that, notwithstanding the high authority of some of our best 

 anatomists, the Bryozoa must l)e removed altogether, not only from the Polyjis, 

 but also from the type of Radiata, and referred to that of the Mollusks. The 

 presence of a Coral stock in most of them can no longer have the slightest weight 

 in determining their altinities; since we have already seen that there is a kind 

 of Coral stock, the Millepora, formed by certain Ilydroids of the same type as 8ertu- 

 laria and Campanularia, or, rather, closely allied to Ilydractinia, which truly Ijelong 

 to the Acalephs ; and since, among the genuine Polyps themselves, we tind Corals 

 so diversified as those of the Astra3aus and Madrepores, of Gorgonias and the Eed 

 Coral, and of Tubipora. Under these circumstances, it must be self-evident that 

 the name of Corals can no longer l)e applied to designate a natural group of 

 animals, but only certain modes of association of animals belonging to very different 



' I luive alreaily insisted upon this poinl in llnise wlio consider tlie AVorms as a distinct branch 



tiie lirst vohime of this work (p. 1 4.'!), an<l in tlie of tlie animal kingdom, and associate with them the 



I'haiitcr on Embryological S3'stenis (p. 2l'(l). Uacr Rotifera and oven the Bryozoa. Witli reference to 



was tlie lirst to estahlisli a clear distinction lictwecn the Bryozoa and I'olyps it is essential to remember, 



the dcgrei' of iK/rfeclion in the structnre of animals tliat, thoiigli the body in both may be called a sac, 



and the jilan upon which that structure is buill, a in Polyiis this sac is a rddiulliig sac, wliile in Bry- 



distinction which C'uvii-r had not reached wlicu he ozoa it is a JiilateraJ sac ; i. e., tlie one is biiilt upon 



allowed the Intesthial Worms to remain among the one plan and the other upon another plan. In 



Radiata on account of the simplicity of their sliuc- Polyps the fundamental idea is radiation, in P>ryo- 



ture. Tlie same confusion remains in the minds of zoa bilateral si/inmetry. 



