[ 274 ] 

 XLVII. Zoological Notices. By Mr. John Edward Grav. 



On the Characters of Zoophytes. 



CINCE the discovery by Ellis, that the corals ami other 

 ^ zoophytes were the houses of animals, there appears to 

 have existed in the greater number of persons a considerable 

 difficultv to thaw the line of demarcation between them and 

 the Marine Algae ; but tins difficulty must have arisen from 

 the consideration of them as animals themselves, and not as 

 the houses of animals, in the same manner as shells are to the 

 Mollusca. For in the consideration of them in the latter 

 point of view, it is impossible that they can contain the ani- 

 mals without a space to hold them ; this space, or at least its 

 mouth, as the animals are always regularly radiated, is con- 

 stantly regular and mostly symmetrical ; so that let the structure 

 be either a simple tube, or many tubes close together or sepa- 

 rated by the intervention of cretaceous matter forming a plant- 

 like structure, they always terminate in a regular mouth. 

 Whereas marine plants are formed entirely of cellular structure, 

 which is condensed on the surface to the form of a cuticle 

 (which is sometimes, as in the Sponges, mucilaginous), and they 

 very seldom have any apertures on their surface, or, if they 

 have, these are always irregular. 



Now since Silex is generally allowed to be found on the sur- 

 face of many Monocotyledones, and Tabashecr in the joints 

 of the Bamboo, why should not chalky matter be found in 

 Alga?? Indeed it is to be seen on the surface and internal 

 structure of several Thalassiophytes which have never been con- 

 sidered as Zoophytes. 



Therefore I should consider none of the marine plant-like 

 bodies to be of animal formation, unless cells could be discovered 

 opening on their surface with regular apertures; and consequent- 

 ly there is no reason why thegenera CoraIli/ia,Dic/iolumaria,Pc- 

 nicilhis, and Flabcllaria, of Lamarck, and perhaps even Nulli- 

 pora of Cuvier, should not be placed with the Alga?. The 

 first of these I have ventured to remove to their ancient habi- 

 tation, on account of their bearing tubercles very similar in 

 appearance to those of many olCcramiadcc or marine conferva? ; 

 and the first section of Flabcllaria, especially Flabcllaria 

 pavonia of Lamarck, bears a very great affinity to, as the above- 

 named author justly observes, if it does not actually belong 

 to the same genus as the Ulva pavonia of Linnaeus, which 

 Draparnaud the elder has formed into a genus under the 

 name of Zonaria. This affinity induced me to place the 

 Corallincc so close to the Zonarice, in my father's Natural 

 Arrangement of British Plants. 



