ZOOPHYTES. 



CHAPTER Y. 



CALCAREOUS ZOOPHYTES. 



All the preceding zoophytes, the naked polypi or hydra? excepted, 

 are compounded of two distinct principles, one of them evidently organic, 

 or carrying on the active vital functions. 



The office performed by the other is not alike evident, and as we 

 have said, it is called inorganic, as much in contradistinction to the former, 

 as from the belief of its defective vitality. 



This second portion consists of different elements, according to the 

 nature of its tenant, as would be found on chemical analysis. Whence, 

 zoophytes are combined with gelatinous, membranaceous, and calcareous 

 formations, as the most obvious principles. Some others, less decided, also 

 enter the inorganic parts. 



The present chapter, miscellaneous like the last, contains a few gene- 

 ral notices on zoophytes, whereof the polyparium is strictly calcareous. 



§ 1. Flustra membranacea. — Plate XXIII. — As an introduction 

 to the subject, a product which is classed with the Flustra, may be de- 

 scribed, while the polyparium, to external appearance, is wholly calcareous, 

 and thence, perhaps, it may be found closely allied to the Lepralia. 



In our present state of knowledge, the precise position of some 

 zoophytes becomes embarrassing ; first, because the leading features of or- 

 ganization do not seem to be definite ; secondly, because no practical 

 observer can possibly enjoy the opportunity of inspecting and studying all 

 the intermediate links connecting genera. These points will always ren- 



