fessor Moseley's interpretation of the Ak-_vou;irian nature of the 

 zooids, associated with the larger pores, is correct. J'lie fact 

 still remains established however, that the exceedingly more 

 numerous smaller ])ores, are inhabited bv a worm allied to 

 Leucodore. To what, if any extent, these annelids contribute 

 to the formation of the corallum of Heliopora, or to the moulding 

 of its characteristic porous structure, remains to be discoA'ered. 

 As so far investigated, the coral is shown to represent a most 

 interesting example of what is jiuowu as " commensalism," or the 

 sharing of a common residence, by two entirely distinct organisms. 

 Much remains yet to fully elucidate the precise relationship that 

 subsists between the two organisms, associated togetlier in 

 HftJiopOiTi cendecf, as also to make known their developmental 

 histories, and respective histiological details. I propose now, to 

 leave this coral as one among the many attractive lures, calculate 1 

 to attract the biological student to the marine laboratory, I 

 hope to see established in the near future, at Thursday Island. 



While on tlie subject of commensalism, a passing I'eference 

 may be made to one or two additional in.stances of this strange 

 natural phenomenon that attracted my attention in the same 

 district. Among the reefs in the neighbourhood of Thursday 

 Island, are some enormous sea anemones, having not unfrequently 

 an extended diameter of at least two feet, and apparently refer- 

 able to the genus Discosoma. One of these has frequently asso- 

 ciated with it a fish, about three inches in length, of a brilliant 

 Vermillion hue, with three broad white crossbands, and which 

 I have identified with the Ainphiprion percula of Lacepede. 

 This fish takes up its abode within the gastric cavity of the 

 anemone, and into which it swims back for refuge afler having 

 been dislodged with a stick. In Day's " Fishes of India," an 

 example of the species is described as having been obtained from 

 the stomach of a sea-anemone, the inference being, however, 

 that it found its way there accidentally, and simply as an article 

 of food. Xo indication concerning its interesting commensal 

 habits is given, either here, or in ^Nlacleay's " Fishes of 

 Australia." where it is also recorded. 



