128 ' ENDEAVOUR " SCIENTIFIC RESULTS. 



Anterior rays protected by a moderately high scaly sheath 

 which becomes lower, and finally disappears posteriorly. 

 Caudal deeply forked. Pectoral falcate, reaching nearly to 

 or a little beyond the anterior straight portion of the lateral 

 line. 



Colour. Silvery, darker above. Operculum with a well- 

 defined, round, black spot. Caudal lobes darker towards the 

 tips. 



Described from two specimens 253 mm. long from the tip 

 of the snout to the end of the middle caudal rays. One is 

 from Port Jackson, New South Wales, and the other from 

 Fremantle, Western Australia ; the latter is figured. 



I have examined a well-graduated series of thirty-one 

 young specimens, 60-170 mm. long, and find them to be 

 separable into two forms, which probably represent two 

 distinct species. In one, the depth is equal to or but little 

 longer than the head, and always less than one-third the 

 length from the premaxillary symphysis to the end of the 

 middle caudal rays ; the other form has a much deeper body, 

 its depth being much greater than the length of the head, and 

 considerably more than one-third the length. A critical 

 comparison of specimens of equal size, however, fails to reveal 

 any other structural differences. 



A similar, but less striking dimorphism is exhibited by 

 ten larger examples, 230-440 mm. long, but my material is 

 not sufficiently well preserved to enable me to determine 

 whether they represent two species. The slender form 

 described and figured here is apparently the true C. georgianits, 

 though I have not seen any specimens with twenty-eight or 

 more dorsal rays as described by Cuvier & Valenciennes. 

 The deeper specimens are evidently C. platessa ; this form is 

 figured by Richardson as C. georgianus 1 . 



Caranx nobilis was evidently founded on a large specimen 

 of C. georgianus. The typical specimen is apparently lost, 

 and no others bearing Macleay's name are now preserved in 

 his museum, but his description agrees very well with Cuvier 

 and Valenciennes' species. 



Locs. Specimens are in the Australian Museum from 

 Moretoii Bay, Queensland ; Lord Howe Island ; Port Jackson. 

 New South Wales ; Adelaide, South Australia ; Fremantle, 



1. Richardson Zool. "Erebus & Terror," Fishes, 1848, p. 135, pi 

 Iviii., fig. 1-3. 



