TRIBE III. MADREPORACEA. 435 



The species of this genus are multiplied in this treatise much 

 beyond what is found in preceding works, the nine of Lamarck being 

 increased to more than sixty. The author has had the advantage of 

 a large collection of specimens from known and unknown regions ; 

 and these specimens, with but two or three exceptions, have been 

 perfect, full-grown clumps, instead of mere fragments. Many of the 

 species would be confounded if studied only from a detached branch- 

 let : even the tall arborescent species, and the spreading cespitose 

 frond, might, in many instances, be thus thrown together. A general 

 survey and close investigation of the subject has rendered the multi- 

 plication unavoidable. Ehrenberg, in his Memoir on the Corals of 

 the Red Sea, describes twenty-one species : but, in most instances, 

 the descriptions are unfortunately concise; and, as they are unaccom- 

 panied by drawings, it has been a perplexing task to identify them, 

 and the more so as the names of Lamarck's species have been given 

 in several instances to species wholly different. 



Arrangement of the Species. 



A. Horizontal or oblique foliate, without proper branchlets above. 



I. Caliclcs tubiform. 



*1. M. palmata. *3. M. flabellum. 



*2. M. alces. *4. M. cyclopea. 



II. Calicles labellate (surface ofcoraUum covered with incipient conical branctdets). 

 *5. M. conigera. 



B. Horizontal or oblique, with erect or ascending branchlets above, which form a clump 

 with an evenly concave or convex top vasiform or cespitose. 



I. Calicles thin labellate. 



*6. M. efflorcscens. *11. M. millepora. 



*7. M. cytherea. *12. M. prostrata. 



*8. M. spicifera. *13. M. subulata. 



*9. M. hyacinthus. *14. M. convexa. 

 *10. M. surculosa. 



II. Calicles quite thin ; round-narifbrm, or appressed-tiibiform. 



*15. M. aculeus. *17. M. tubicinaria (suffruticose). 



*16. M. tenuis. 



III. Calicles stout, nariform or tubiform. 



*18. M. paxilligera. *21. M. globiceps. 



*19. M. nasuta. *22. M. effusa. 



*20. M. digitifera. *23. M. corymbosa. 



