80 



interesting observation was made, with reference to the variation 

 of colour that may exist among the polyps belonging to the same 

 corallum of EuphylUa fflahresceiis, and with relation to the 

 amount of light to which they are exposed. An exam])le noticed 

 was so growing that certain of the polyps projected ui'derneath, 

 and were completely concealed from the light by surr(nuiding 

 coral growths ; here the tentacrles were transparently white, with 

 pale primrose-coloured tips. Where the light only ]xirtially 

 fell on them, the tentacles were sai^e-green, with brighter yellow 

 tips; while, in the fully exposed area, all the tentacles were dark 

 brown, with deep golden terminations. Analagous ill ustrations of 

 the effect on the colours of the coral animals, produced by the 

 absence of light, were also observed by me among representatives 

 of the genera Mussa and Galaxfci, and in which the polyps were 

 similarly bleached, after the manner of cultivated celery and sea- 

 kale when screened from the light. Examples of Euphyllia in a 

 condition of semi-extension, illustrating the characteristic 

 structure of the polyps, were also successfully photographed. 



A remarkably beautiful coral, that occurs in tolerable abundance 

 in the vicinity of Thursday Island, is a representative of the same 

 family of the EuphylliiJce, and is known to science by the name 

 of PJeroqijra laxa. It consists of clusters of polyps, united in 

 undulating linear series. As seen in their expanded state, the 

 centres of the polyps are emerald green, variegated with brownish 

 striae, while the tentacles are primrose or lemon yellow, with 

 brilliant lilac or magenta tips. In their fully extended state, the 

 tentacles are over an inch in length, and the lilac tips are 

 spherically intiated. When, however, only partially extended, as 

 represented in the photogra])hs secured, the tentacles do not 

 exceed half-an-inch in length, and are simply terete. 



One of the most interesting coral.>*, that grow.s abundantly in 

 the same district, is the form popularly known as the organ pipe 

 or music coral, Tiibipora musica. The species takes its name 

 from the fancied resemblance of its corallites to the pipes of an 

 organ. The corallum of Tubipora is remarkable for its deep 

 crimson hue, while the polyps, by which it is secreted, are pale 



