22 Prof. J. W. Gregory on the 



whose opinion was no doubt formed independently, as he does 

 not refer to Prof. Heilprin's paper. In Brook's great mono- 

 graph of the genus Madrepora he not only merged Lamarck's 

 three West- Indian species, but adopted for them Linnaaus's 

 name of muricata. 



During a recent visit to the West Indies I have had the 

 opportunity of studying the three forms of Madrepora on the 

 reefs, and have been led to revert to the Lamarckian arrange- 

 ment. As in 1895* I accepted Brook's proposals, it may be 

 advisable to state the reasons for my change of opinion. 



It will be convenient first to consider whether the West- 

 Indian Madreporce are all to be included in a single species. 

 Brook supported this idea by two lines of evidence : — 1st, the 

 distribution of the corals on the reefs ; 2nd, the existence of a 

 series of specimens having characters intermediate between 

 those of Lamarck's species. 



Habit and Environment. 



The first argument was based on statements that Brook 

 attributed to Pourtales. Thus he says t that Pourtales has 

 " hinted that the three species of Lamarck may prove to be 

 variations of one species, dependent on environment for their 

 precise habit." But this is not quite a correct account of 

 Pourtales's opinion. The only reference to Pourtales which 

 Brook includes in his synonymy is to the memoir on the 

 " Deep-sea Corals." Therein Pourtales J does hint that possibly 

 M. cervicornis and M. proh'fera may be specifically identical ; 

 but he makes no suggestion that M. pahnata should be 

 united with them. He even comes finally to the conclusion 

 that M. cervicornis and M. proh'fera may be conveniently 

 kept apart. The passage referred to is as follows : — " Some 

 specimens partake so much of the characters of both this 

 [i. e. M. proh'fera'] and the preceding species [M. cervicornis] 

 as to shake the belief in their specific difference. IStill the 

 greater number of specimens examined are readily distin- 

 guished, more perhaps by their habitus than by the more 

 minute characters of the calicles." 



Pourtales's conclusion seems to me sound. Specimens of 

 M. proh'fera and M. cervicornis are distinguishable without 



* J. W. Gregory, " Contributions to the Palrecntology and Physical 

 Geography of the West Indies," Quart. Journ. Geol. Soc. vol. li. (1895) 

 p. 282. 



t Brook, op. cit. p. 18. 



\ L. F. de Pourtales, " Deep-sea Corals,'' 111. Cat. Mus. Comp. Zool. 

 no. iv. 1871, p. 84. 



