188 Prof. F. M'Coy on the Australian Species of Arripis. 



Centropristes or Arripis salar of Richardson and Gunther's 

 works. They have the belly silvery, back olive, sides rich green 

 with vertical darker bands, and four or five longitudinal rows of 

 round yellow spots, like lacquered brass, on the sides. This 

 style of colouring, so different from that of the adult, is most 

 strongly marked in the young of three or four inches in length; 

 and 1 have traced in the most gradual and satisfactory way its 

 gradual confusion and obliteration as the size approaches 1 

 foot, beyond which only traces can be seen of any difference 

 from the nearly uniform dull colouring of the adult. The su- 

 perior size of the eye, the difference of proportional distance 

 between the orbits, and the shape of the forehead, relied upon 

 by authors amongst the characters separating the C. Georgianus 

 from the others, are more and more exaggerated as the size and 

 age of the individuals are less and less. 



In small, very young individuals the posterior edge of the 

 prfeoperculum is not denticulated ; and this is the great charac- 

 ter relied on by Cuvier and Giinther for the specific distinction 

 of the C. truttaceus in their works (the fin-rays of the adult 

 varying to the amount I have shown above) ; but I have clearly 

 demonstrated the gradual appearance and development of the 

 serration with increase of size; so that this is certainly (as might 

 even be seen by observing the relative lengths of the radiating 

 ridges forming the denticles going to the posterior and inferior 

 edges of the prseoperculum respectively in an old fish) only a 

 character of immaturity. 



Living specimens of the young fish three or four inches long 

 have the caudal fin bright yellow, with a broad posterior margin 

 of rich black ; both these colours fade quickly, and totally dis- 

 appear in spirit or on a dried skin. Now as this particular 

 colouring, noted by Cuvier on a drawing from life of a fish of 

 which he had never seen a specimen, was the foundation of the 

 species Perca marginata in his ' Histoire Naturelle des Poissons/ 

 and all the other characters are those found likewise in the 

 young of Arripis Georgianus, I have no doubt, from my observa- 

 tion of these fugitive colours in the living fish, that Perca 

 marginata should be added to the synonyms of the one Australian 

 species of Arripis found here — the A. Georgianus. I mean to 

 publish figures from the life, shortly, in the ' Decades of the 

 Prodromus of the Zoology and Palaeontology of Victoria/ which 

 I am preparing as part of the " Memoirs of the Melbourne 

 Museum," the establishment of which occupies all my leisure so 

 pleasantly. 



Melbourne, June 24, 1865. 



