ANIMALS. 21 



of the polyps. The first sub-class may be conveniently divided into two orders, 

 Hydroida and Actinoida ; but the second does not as yet appear to be resolvable into 

 more than one, for which it is intended to use in a popular sense the name Bryozoa, 

 originally proposed for the group itself by Ehrenbcrg. In the first and lowest order, 

 Hydroida, digestion is performed by the secretion of a simple sac excavated in the 

 gelatinous and granular substance of the animal's body. In the second, Actinoida, the 

 digestive sac, which, like the first, throws out the rejectamenta by the same aperture 

 as that which receives the nutriment, is suspended b}^ a series of vertical folds of 

 membrane, in a distinct abdominal cavity, to the outer parietes of the body. In the 

 sub-class Ciliohrachiafa, the alimentary canal, which is likewise suspended loosely in 

 an abdominal cavity, is provided with a distinct mouth and outlet.^ 



It is uncertain whether the whole of the orders just noticed have representatives 

 amongst the Corals hereafter to be described. There are strong objections to any of 

 them being considered as Hydroidas ; but there is nothing to oppose the placing of 

 most of them in the other divisions. 



Sub-class NuDiBRACHiATA, Farre. 



Waiving the Hydroida, for the reason just stated, it is proposed to pass at once to 

 the order Adinoida established by Dana, who divides it into two sub-orders, Actinaria 

 and Alcyonaria. 



Sub-order Actinaria, Dana, 1847. 



ZoocoRALLiA POLYACTINEA, Ehrenberg. 

 ZoANTHA, BlainviUe. 



Les Zoantaires, Audouin et Milne Edwards. 

 ZooPHYTA HELiANTnoTDA, Johnston. 



Diagnosis. — " Tentacles six, twelve, or more in number, not papillose (with few 

 exceptions), and perforate at the apex ; often coralligenous ; coralla calcareous, very 

 rarelv corneous, cells radiate with lamellae."" (Dana.) 



The members of this division arc represented on the British coasts by the naked 

 Actinias or Sea Anemones, everywhere distributed on our rocks ; by the single species 

 Zoantlius^ Couchii, which seems to be confined "to the Cornish part of the British 

 Channel ;" and by a few forms of lamelliferous Corals rarely to be met with in northern 



' Vide Owen's Lectures on the Comparative Anatomy and Physiology of the Invertebrate Animall, 

 p. 82. 



- Structure and Classification of Zoophytes, p. 113, 1847- 



