144 



SCIENCE. 



[N. S. Vol. XV. No. 369. 



has been possible to bridge over a large num- 

 ber of the gaps which separate certain so- 

 called species, and to demonstrate that many 

 of the latter are but varieties of growth in a 

 somewhat protean group. Thus, to take a 

 couple of instances : Oriicella acropora 

 (Linnseus) now embraces ten species, and has 

 been known under the same number of genera ; 

 Meandrina meandrites (Linnseus) has a 

 synonymy in which are represented seven 

 genera and thirteen species. 



Unfortunately the revision of the synonymy 

 reveals the necessity for several important 

 changes in long-established names if the 

 rules of nomenclature are to be strictly fol- 

 lowed. Vaughan now shows that the true 

 Meandrina is not the brain coral which stu- 

 dents, from the time of Milne-Edwards, have 

 been accustomed to associate with the name, 

 but is the Pectinia of Milne-Edwards, while 

 the Meandrina of the 'Coralliaires' has for 

 the future to be known as Platygyra. It is 

 with a sigh that one relinquishes Madrepora 

 for the corals so long associated with this 

 name. As was first pointed out by Geo. Brook, 

 in the British Museum Catalogue of the 

 Madreporaria, none of the species at present 

 included under Madrepora were embraced by 

 Linnaeus when he instituted the term in 1768. 

 Vaughan now suggests its replacement by 

 Isopora, a name first used in the subgeneric 

 sense by Studer in 1870. 



The writer follows Brook in regarding all 

 the forms of the West Indian Madrepora as 

 but one species, the three Lamarckian species 

 — palmaia, cervicornis and prolifera — being 

 reduced to formae or varieties. Gregory in 

 1895 had come to the same conclusion as 

 Brook, but in 1900, following upon a visit to 

 the West Indies, and the opportunity of seeing 

 the different representatives in situ, he reverts 

 to the Lamarckian arrangement, and en- 

 deavors to dispose of the specimens which 

 Brook regarded as intermediate in form. 



In the immense coral flats around the vari- 

 ous Antillean islands the three types of 

 Madrepora growth usually retain a remarkable 

 distinctness of form, though often growing side 

 by side; and from a study of these alone one 

 would be far from induced to admit their 



specific unity. The polyps, however, are prac- 

 tically alike in form and color, and anatomi- 

 cally and histologically they reveal no im- 

 portant differences. Vaughan also believes 

 that he possesses colonies which should be re- 

 garded as intermediate in habit between the 

 three recognized types. In his forthcoming 

 Porto Rican paper the author proposes in like 

 manner to unite under two groups the many 

 and varied West Indian representatives of the 

 allied genus Porites. 



It might have been supposed that the study 

 of the polyps themselves, both in their living 

 condition and anatomically and histologically, 

 would have revealed distinctions tending to 

 strengthen the specific separations founded 

 upon the skeletal form. But such is not the 

 case. A comparative study of the polyps of 

 many so-called species of Madrepora, Porites, 

 Orhicella, etc., now in progress reveals very 

 few differences within each genus. Compared 

 with those of Madrepora the polyps of Porites 

 vary greatly in color, often on the same 

 colony, but except for slight variations in size 

 no other differentiations of importance can be 

 established in any part of their structure. 



Extensive studies like those now being un- 

 dertaken by Vaughan indicate that the greater 

 the number of specimens of Madreporarian 

 corals which are studied, with regard both to 

 the skeleton and soft parts, the greater will 

 be the tendency to lessen the number of 

 species. As it has been expressed by the au- 

 thor: "The number of species is very often a 

 function of the amount of the material 

 studied." The same tendency has already 

 reached its climax in the case of the Hydro- 

 zoan coral, Millepora. In the course of a 

 study of both polyps and skeleton of this 

 genus, extending over many years, and em- 

 bracing specimens from all parts of the world. 

 Professor Sidney Hickson has recently come 

 to the conclusion that it is impossible to main- 

 tain any specific distinction. All the numer- 

 ous skeletal forms, hitherto included under 

 about thirty-nine names, are, from Hickson's 

 researches, to be regarded as but so many 

 varieties of growth, which presumably may be 

 assumed by any one individual under like 

 conditions. 



