on the Organic Composition of Chalk and Chalk Marl, 301 



In the preceding Table we see that of the forty-three genera 

 of Zoocorallia, there are eight which are found fossil; the 

 living species amount to 151, of which fifty-four exist in the 

 Red Sea, and forty-nine of these have been observed by the 

 author, five remaining unproved. Of the forty-three genera 

 of Phytocorallia there are twenty-seven which are found fos- 

 sil; the living species amount to 235, of which sixty-six exist 

 in the Red Sea, and sixty-one of these have been observed by 

 the author, five remaining unproved. The general result is, 

 that out of eighty-six genera of Anthozoa, thirty-five occur in 

 the fossil state; and that of 386 known living species of An- 

 thozoa, 120 exist in the Red Sea, of which 110 species were 

 observed by the author. The same Table also shows that of 

 the seventeen families of known Coral animals, thirteen exist 

 in the Red Sea, while four are wholly wanting, namely, those 

 of Pennatulina, Hydrina, Tubularina and Alloporina. The 

 total number of known living species com.prised in each family 

 is also given, as well as the relative number actually existing 

 in the Red Sea, 



The 120 species of Anthozoa existing in the Red Sea thus 

 constitute nearly one third of the whole number of living spe- 

 cies, and being comprised in forty-four genera, the latter rather 

 exceed one half of the number of known living genera. 



Of the known living Corals there are eight genera peculiar 

 to the Red Sea, namely, Megalactis, Thalassianthusl ^ Epi~ 

 cladia, Heterodactylai Anthelia, Ammothea^ Stephanocora and 

 Strombodes. It appears also that eighty-eight species are pecu- 

 liar to it, not having been hitherto observed anywhere else. 



Among the genera of the Red Sea that o^ Strombodes excites 

 peculiar interest, having previously been found only in the fos- 

 sil state. It affords a key to the structure of the remarkable 

 Cyathophylla, diflfering from the view hitherto entertained, 

 and rendering it quite clear that the internal central star of 

 the encased forms is not a young one, but the oldest or mo- 

 ther star, which is often surrounded by broad radiated mantle- 

 folds productive of buds. 



It appears probable that the Red Sea and the part of the 

 Mediterranean so nearly adjoining on the Libyan coast, pos- 

 sess only two forms out of the 120 species in common, namely, 

 Acti?iia Tapeium and A. Mesembryanthemum, 



Of the Bryozoa group. Dr. Ehrenberg gave in the same 

 memoir, contained in the volume of the Transactions for 1832, 

 only the more general results of his investigations, without en- 

 tering into detail ; but the subject is resumed in his later me- 

 moir, inserted in the volume for 1838, in which he has pre- 

 sented a tabular view of the Bryozoa, distributed into Orders, 



