ANNOTATIONS AND ADDITIONS. 63 



up islands from fathomless depths of the ocean. They 

 excite the liveliest interest, whether considered as subjects of 

 physiology and of tlie stady of the gradation of animal forms, 

 or whether they are regarded in reference to their influence 

 on the geography of plants and on the geological relations 

 of the crust of the Earth. According to the great views of 

 Leopold von Buch, the whole formation of the Jura consists 

 of " large raised coral-banks of the ancient world surround- 

 ing the ancient mountain chains at a certain distance." 



In Ehrenberg's Classification, (Abhandlungen der Akad. 

 der Wiss. zu Berlin aus dem, J. 1832, S. 393-432) Coral- 

 animals, (often improperly called, in English works, Coral- 

 insects) are divided into two great classes : the single- 

 mouthed Anthozoa, which are either free or capable of 

 detaching themselves, being the animal-corals, Zoocorallia ; 

 and those in which the attachment is permanent and plant- 

 like, being the Phyto-corals. To the first order, the 

 Zoocorallia, belong the Hydras or Arm-polypi of Trembley, 

 the Actiniae decked with beautiful colours, and the mushroom- 

 corals ; to the second order or Phyto-corals belong the 

 Madrepores, the Astrseids, and the Ocellinae. The Polypi 

 of the second order are those which, by the cellular wave- 

 defying ramparts which they construct, are the principal 

 subject of the present note. These ramparts consist of an 

 aggregate of coral trunks, which, however, do not instantly 

 lose their common vitality as does a forest tree when cut 

 down. 



Every coral-trunk is a whole which has arisen by a forma- 

 tion of buds taking place according to certain laws, the 



