Zoophytes. 205 



the surface, like the Cirripedes ; and others, as the Magillus and Serpu- 

 lae, being attached to the surface, and lengthening their tube as the 

 frondose expansions of the coral to which they are attached enlarge, 

 so that they may be able to procure their fair share of nutriment, and 

 not be starved, as they would be if the animal of the coral overtopped 

 them. 



These cases are common enough, but I have a specimen from the 

 Rev. Mr. Guilding's collection which shows a much more uncom- 

 mon instance. It is an expanded coral, which forms a thin surface on 

 the top of another coral, and is furnished with a number of small, de- 

 pressed, horizontal cases, opening with an oblong mouth. Some of 

 these contain within them a small, free, crustaceous animal, a Cy- 

 mothoa, which nearly fits the case ; and it is evident, that by their 

 moving backwards and forwards on the surface, they have caused the 

 animal of the coral to form one of these cases for the protection of 

 each specimen. 



The animals which form their habitation in corals, appear to begin 

 their domicile in the same way as the barnacles before referred to : 

 they take advantage of the soft and yielding nature of the animals 

 which form the corals &c., and taking up a lodgment in their body, all 

 they have to do is to keep a clear passage in it, either by the moving 

 backwards and forwards, the exertion of their limbs, or the ingress and 

 egress of water to and from their bodies, and in time, as the coral is 

 secreted by the animal, it will form a wall round them ; but if, by any 

 accident, the parasitic animal should not keep its passage from the 

 coral to the surface of the body of the animal clear, which it must 

 be constantly induced to do, since by this means it procures its food, 

 the coral animal will in a very short time close over it and bury it 

 alive in the mass of the coral ; and this, from the number of these 

 animals, of all sizes and in different stages of growth, which are to 

 be found in the substance of the large and massive corals, must often 

 be occurring. Thus the Italian romance is often literally fulfilled 

 in Nature. J. E. Gray. 



Notes on the vitality of the sheath of the Hydroidce. 

 By R. Q. Couch, Esq., M.R.C.S.L. 



An opinion is entertained by some naturalists that the polypidoms 

 or solid parts of most zoophytes are extravascular and inorganic, 

 and consequently, when once formed, are for ever placed beyond the 



