BRYOZOA. 29 



Balanophyllia, all reputed extinct, although the first is very 

 closely related to the living Splwnotrochus Macandrewi. 



The total number of fossil corals enumerated by M. 

 d'Orbigny in the "Prodrome de Paleontologie," amounts to 

 1135, grouped under 216 genera. But notwithstanding all the 

 labour which has been bestowed on this branch of paleonto- 

 logy by Groldfus, Michelin, Lonsdale, and Milne Edwards, 

 species are continually discovered or brought home from 

 abroad which are altogether new, and cannot be placed in any 

 of the constituted genera. 



Class III.— BEYOZOA. 



Char. — Tentacles of the polype hollow, with ciliated margins ; 

 alimentary canal with stomach, intestine, and anus; 

 polypary, when present, external, horny, and calcareous. 



The metamorphoses which the Bryozoa undergo are like 

 those of the lower Polypi; the embryo developed from the 

 ovum is an oval, discoid, or subdepressed body, with a general 

 or partial ciliated surface, by which it enjoys a brief locomo- 

 tive life after its liberation from the parent. The Bryozoa are 

 allied to the compound Ascidia ; but not one of the ascidian 

 Molluscoids quits the ovum as a gemmule swimming by 

 means of cilia ; and no Bryozoon quits the ovum in the guise 

 of a Cercarian or tadpole, to swim abroad by the alternate 

 inflexions of a caudal appendage. In a progressive and con- 

 tinuous series of teachings, by pen or word of mouth, the 

 place of an osculant or transitional group is governed by 

 convenience, by considerations of how best to teach by 

 comparison and easy gradation; and the Bryozoa, whether 

 regarded as the highest organized Badiates, or as the lowest 

 organized Mollusks, are treated of accordingly, in the position 

 here assigned to them. The practical palaeontologist finds him- 

 self compelled, indeed, to arrange, and study the fossil Bryozoa 



