194 "ENDEAVOUR" SCIENTIFIC RESULTS. 



Colour. See under variation. 



Described and figured from an adult male, 56 mm. 

 long, from Masthead Island, Queensland. A female of 

 similar size is also figured. 



Variation. A series of thirty specimens, 18-55 mm. 

 long, exhibits very little variation in structural 

 characters, but includes two very different types of colour- 

 marking which appear to be distinctive of the two sexes. 

 Young examples are almost uniform brown with lighter 

 coloured pectoral, ventral and anal fins; several rows 

 of narrow, slightly oblique and dark lines are usually 

 present on the membrane between the rays of the dorsal 

 fin, but they may be obscure in darker specimens. Of the 

 two colour-variations exhibited by full grown specimens, 

 one (female PI. li, fig. 1) is light brownish-yellow in 

 general colour ; the dorsal fin is usually marked with dark 

 horizontal lines as in the young, and the caudal fin has 

 a faintly darker inframarginal border. The other (male 

 -PI. li, fig. 2) is dark brown with the sides of the head 

 and breast yellow ; a broad light-coloured baud extends 

 backward from the head, and may reach the caudal 

 peduncle or terminate below the dorsal fin ; indications 

 of the dark lines may persist. The upper and lower 

 portions of the caudal fin are crossed by broad light- 

 coloured bands. Pectoral and ventral fins light-coloured. 



These markings vary in intensity, being distinct in 

 some and obscure in others. The fact that I have 

 collected both forms at three different localities, Mast- 

 head Island, Murray Island and the New Hebrides, com- 

 bined with their similarity in all structural details, con- 

 vinces me that both are referable to the one species. 

 Dissection of two specimens reveals roe in the light- 

 coloured form, and milt in the darker example. 



Localities. Reef at Masthead Island, Capricorn 

 Group, off Port Curtis, Queensland; coll. McCulloch, 

 September, 1904. 



Reef at North-west Islet, Capricorn Group, off Port 

 Curtis, Queensland ; coll. H. C. Daunevig, 10th July, 1910. 



Cairns Reef, off Port Douglas, Queensland; coll. 

 McCulloch, September, 1909. 



Reef at Murray Island, Torres Strait; coll. 

 McCulloch and Hedley, October, 1907. 



New Hebrides; coll. McCulloch, September, 1910. 



