MADREPORARIA. 757 



from Rotuiua and Funafuti, in each species however the specific characters being clearly 

 recognisable. Indeed, there would appear to be a locality mode for certain characters in 

 each genus, a fact which Mr Bernard's catalogue of Goniopora certainly illustrates. The 

 characters, which thus vary, may be all to some extent vegetative, but can they be entirely so ? 

 They do not, so far as my study has gone, seem to include the characters on which the 

 species in any genus are founded, whereas discontinuous variation chiefly affects these 

 characters. The differences in the specimens between the different localities referred to are 

 small, but, if they be due to natural selection, the logical result of its action would be to 

 produce ultimately fresh genera with parallel species. There is no sign of any such action 

 going on at the present time. Coral genera are extremely widely spread, and the same sj)ecies 

 are found in widely separated regions. If, as seems probable, such species are not found 

 in intermediate regions, this fact would point to their presence in these distant regions as 

 due either to the fixation of such a number of discontinuous variations as form their specific 

 characters, in a word to the parallel formation of discontinuous variations, or on the other 

 hand, to the particular species having once extended over the whole area and been killed 

 out or altered in the intermediate areas. The difficulties in respect to the last view are 

 obvious, when one considers the W. and E. Indies, or the Red Sea or Maldives and the 

 Philippines, but it is useless discussing the matter further until we have definite accounts 

 of considerable collections of several genera from different localities. 



With regard to the species question in corals I can only say that I have not found the 

 same difficulty with the Astraeidae that Mr Bernard has certainly experienced in the perforate 

 genera. The species seem definitely separated and constituted, and I feel reasonably certain 

 that I am dealing with definite species or varieties. Before attempting to name, I sorted 

 each genus into its species, a task in which I was much assisted by my notes above referred to, 

 placing under each specimen a paper with measurements and notes of all such characters 

 as seemed to me to be specific in its genus. I then proceeded in the usual way, but I have 

 been much aided by criticism from Prof Jeffrey Bell and Mr Bernard, and the kindness of 

 these gentlemen in assisting me on many occasions in examining the British Museum collections. 

 The difficulties of the work can only be appreciated by those who have examined sedentary 

 organisms. Many of the so-called species are described on extreme vegetative varieties, or 

 on single small specimens from unknown localities, very commonly without figures, while in 

 many descriptions all reference to half or more of the specific characters is omitted. 

 Considering the dates of their publication, I can only pay a high tribute to Milne-Edwards 

 and Haime's great work, Histoire des Coralliaires, and Klunzinger's Die Korallthiere des 

 Rothen Meeres, in referring to each of which I have merely mentioned the page and figures 

 under their authors' names. I have also adopted the same course in reference to Dana's 

 Zoophytes and my paper on my Pacific Ocean Astraeidae (Proc. Zool. Soc, 1899, j). 734). 

 References to other literature will be found in the above works ; I have in the majority of 

 cases not given other references unless they throw some definite light, that the above do not, 

 on the species under consideration. I am particularly indebted to Klunzinger's interpretation 

 and photo-figures of Ehrenberg's specimens. It is to be hoped that the same may be done for 

 Duchaissaing and Michelotti, and also that Prof Verrill will figure the species that he has 

 described. However, I am not much affected by the work of these authors, since the 

 American species, on which they principally worked, are taken altogether widely different 

 from the Maldivan. 



97—2 



