1907.] AND SUPPOSED SPECIES IN CORALS. 555 



species of corals is by no means so great as is at present 

 supposed. 



There is no doubt that a great number of our museum-made 

 species are mere vegetative varieties, produced in response to the 

 demands of the environment ; and I do not think it is possible 

 to determine from a fragment of growth — often with no sufficient 

 data — if it be a new species, or even a new genus, or if it be a 

 merf) vegetative variety of some already well-known species. 



There can be but little utility in the naming and describing, 

 with great minuteness, of all these variations ; for of this work there 

 can be no end, and persistent collecting, from even such a small 

 area as the Oocos-Keeling atoll, would yield such a variety of 

 fragments as would occupy a lifetime to describe. 



In very many cases one single colony could be found to provide 

 several types of growth, that if presented as fragments, would be 

 deemed to merit individual description as species. 



In such cases some factor in the physical condition of the 

 surroundings will show, when the colony is in sitic, the cause of 

 these different modes of growth ; but when the colony is trans- 

 ported to a museum, it presents a very striking puzzle. 



One side of a colony may be shaded from light, sheltered from 

 currents, or protected from silt ; whilst the other side may be 

 exposed to all these influences : and then it is but natural that the 

 two sides should vary, and — knowing the wonderful plasticity of 

 the zooids — the great differences are not astonishing. 



Besides the occurrence of colonies that exhibit two or three well- 

 marked types of growth, there are those that can only be called 

 " undecided " forms, and these present growths that are inter- 

 mediate in character between two well-marked, and veiy diverse, 

 types. Such "undecided" forms are very common, but it is the 

 natural instinct of the collector to pick out well-marked and 

 well-grown forms as his specimens. 



I have not inckided MiUepo7'a in these remarks, but the genus 

 is well woi'thy of notice ; and although the three types — Jlillepora 

 alcicoi'nis, M. complanata, and M. verrucosa — occur in great 

 abundance in the atoll, and pi-esent very different appearances in 

 their extreme forms, I do not doubt that there is but one sjoecies 

 of Millepore, with three variations of vegetative growth, and an 

 infinity of gradations connecting them. I do not doubt either 

 that all the forms of Pocillopora that are found in the atoll are 

 in reality one species ; and I sti'ongly suspect that thei'e is only 

 one species of Montipora in Cocos, although its varieties are 

 legion. The species of Madrepora in the islands are in reality 

 very few, many diverse forms are certainly identical species, but 

 experimental breeding must finally settle how few these sj)ecies 

 are. 



It is the same throughout the whole series of the Cocos- Keeling' 

 corals ; there is a very limited number of species ; and I would 

 account for the origin of the many varieties, and the present con- 

 fusion of their nomenclature, by the alteration of environment 



