1846.] Structure and Classification of Zoophytes. 26 1 



cavity only, but without a distinct vasculai' or nervous system, and 

 no senses but taste and touch. The tenement of life is here re- 

 duced to its lowest condition — a sort of sack, closed at one ex- 

 tremity, which is apparently homogeneous, and whose vitality 

 animates equally every particle, so that it may be turned inside 

 out without injury or interruption to its limited functions. To 

 maintain life they must remain in the element in which they live, 

 for upon it depends the expansion of their bodies and tentacles 

 and the ejection of their fluids. 



These flower-animals are reproduced in three modes. 



1. By o\'ules either proceeding from within outwards, or from 

 vertical lamellae in the visceral cavity, and which are ejected 

 through the mouth. 



2. By buds or gemmae, which afterwards become free and in- 

 dependent animals. 



3. By artificial sections. 



Zoophytes are either simple or compound, a solitary animal, 

 or a cluster of animals, whose combined gro\^ih has some deter- 

 minate form. They may, or may not secrete a hard stony sub- 

 stance termed by Mr. Dana coralltcm, or what is familiarly called 

 coral, which is analagous to an internal skeleton, inasmuch as it is 

 really invested with the soft parts of the animal. 



Such are the general characters of Zoophytes, whose beautiful 

 forms clothe the shelving shores of tropical seas, and impart splen- 

 dor to the marine fields which are decked with robes as gorgeous 

 as those of our western prairies. 



Mr. Dana divides corals into two orders. 1. Order Hyproi- 

 DEA. 2. Order AcxixoroEA. The first embraces those corals 

 whose visceral cavity is a simple sac, and whose reproductive func- 

 tions reside only in the walls of the cavity. The second includes 

 those whose visceral cavity is divided vertically by fleshy lamella 

 and which possess in them the reproductive functions. Hence the 

 ovules are ejected through the mouth. The first contain the minute 

 polyps, and when the coral is secreted it is horny or membranous ; 

 they are delicate and compound, and exist in the form of little 



