76 PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



The Murray Island specimens show response to environmental conditions 

 similar to that exemplified by the specimens from Cocos-Keeling. All except those 

 from the Lithothamnion ridge have relatively attenuate branches, while those from 

 it have the brevicornis growth facies. But on those of the latter facies between 

 the thicker branches and peripherally below them there are some more slender 

 branches. This response to smooth and rough water is general where the same 

 species of a branching coral lives in the two kinds of environment. I have noted 

 it in discussing the Hawaiian corals, and instances (especially Porites clavaria) 

 were observed in Florida. 



Habitat, etc., Cocos-Keeling Islands.— Dr. Wood Jones has submitted 6 speci- 

 mens taken from a floating log. He has published two accounts of them. 1 In 

 the first of the citations he says: 



"In the lagoon, a large portion of a tree-trunk was floated, and made fast to an anchor 

 and chain; the wood was used to float a ship's moorings, and remained just two years in the 

 water When it was removed in 1906, several colonies of Pocillopora had started growths 

 upon it, and they had taken up different positions around its circumference. The colonies 

 growing above were flattened bosses; those on the sloping sides showed more tendency to 

 branch; and those below its convexity were delicate branched forms. 



" Now the environments of these colonies were very different, and they were absolutely 

 constant. At all stages of the tide waves broke upon its upper surface, whilst the^sides 

 were in gently moving unbroken water, and the bottom was in comparative calm. 



A careful study of the specimens shows that there is in all of them a tendency 

 toward diffuse branching, but in the uppermost specimen the branches are reduced 

 to swollen verruca scattered over the surface; in the next set of three there are 

 slender branches around the periphery near the base. The calicular characters 

 are similar in all. The septa and columella are rudimentary or obsolete, except 

 on spreading basal expansions, where they may be distinct. This lot of specimens 

 is very similar to P. cespitosa Dana. 2 The suite of specimens of the latter which 

 I described from the Hawaiian Islands shows similar and perhaps even greater 



variation. . 



Distribution— -Indian Ocean; Amboina; Fiji Islands; represented in Hawaiian 

 Islands by the closely related, if not identical, P. cespitosa. 



Pocillopora damicornis (Pallas) Dana. 



Plate 21, figure 2, specimen identified as P. damicornis by Dana; figures 3, 3a, specimen from Cocos-Keeling Islands. 



1846. Pocillopora damicornis Dana, U. S. Expl. Exped., Zooph., p. 527, plate 49, figs. 7, 7a. 

 1907. Pocillopora Wood Jones, Proc. Zool. Soc. London for 1907, plate 17, fig. 30. 

 1910. Pocillopora Wood Jones, Coral and Atolls, p. 90, text-fig. 25a; p. 91, text-fig. 26. 



One of Dana's original specimens, from Singapore, is in the U. S. National 

 Museum, No. 660. It seems that it is not the one figured, but it agrees in essen- 

 tials with Dana's figures and the detail of figure J a might have been taken from 

 it. Esper's figure (Fortsetz., plate 37) presents its characters fairly well. 



Habitat, etc., Cocos-Keeling Islands. — Dr. Wood Jones has submitted 3 imma- 

 ture specimens and 2 pieces from mature colonies. The specimen figured by him 

 is nearly typical of the species. He says: "The colonies are of wide distribution in 

 the lagoon and on the barrier flats. Usual color brown; exposed parts of the 

 zooid brown." 



Distribution. — Cocos-Keeling Islands; Singapore; Fanning Island (collected by 

 Carl Elschner). 



'Proc. Zool. Soc. London for 1907, pp. 535-536, pi. 28, fig. 3; Coral and Atolls, pp. 99, 100 (fig. 33, p. 99). "9«°- 

 2 See Vaughan, U. S. Nat. Mus. Bull. 59, plates 10-14. 



