ASTR-ffiOPORA. 



INTRODUCTORY. 



The small genus Astrccopora calls for little introductory comment. It very naturally follows 

 the two genera Madrcpord and Turbinaria, already catalogued, as the three form a well- 

 demarcated group of coenenchymatous corals, i. e. of corals out of the development of which 

 one of the two elements of the typical coral skeleton has practically dropped. In aU these 

 tlie epitheca appears in the earliest stages alone, persisting only in certain explanate forms, 

 while the great mass of the coral substance is built up entirely by the septa and their synap- 

 ticular connections, forming together the cccnenchyma. The genus Astrccopora may, perhaps, 

 be described as consisting typically of glomerate coenenchymatous corals, in contrast on the 

 one hand with Madrcpora, consisting typically of branched, and on the other with TurUnaria, 

 consisthig typically of foliate coenenchymatous corals. 



The three do not lend themselves to any trustworthy phylogenetic arrangement. It is 

 safest to deduce them independently from some more primitive ccenenchymatous coral, 

 which is now, perhaps, only represented in the earliest encrusting stages of Astrccopora and 

 Madrcpora. 



The relation between these three corals and Montipora and Poritcs, which are also 

 coenenchymatous corals in which the epitheca plays an equally subordinate part, will be 

 discussed in the next volume. 



HISTORICAL. 



The genus Astra:opora was founded by de Blainville,* in 1830, to contain certain 

 specimens which he separated from Lamarck's genus As(ra:a. In the work above quoted, 

 he selected seven of Lamarck's Astra:w, viz. A. mi/riophthalma, A. stcllulata, A. pntlfinaria, 

 A. rclifurmis, A. ollvpua, A. palifera, and A. ininctifcra.^ Further study of Lamarck's speci- 

 mens, however, induced him, in 183-i,J to replace A. retiformis among the Astraa, to omit 

 A. oUiqvM,^ and to place A. palifera in the genus Gemmipora {Turbinaria). 



* Dictionnaire des Sciences Naturelles, Ix. p. 348. 



t Cf. Lamarck's Animaux sans vertebres, ii._(1816) p. 260. 



% Manuel d'Actinologie, p. 383. 



§ I have so far not succeeded in ascertaining the fate of this species. 



