120 A NEW FAMILY OF AUSTRALIAN FISHES, 



genera which are here segregated have little in common with the 

 true Mugilids, but form conjointly a connecting link between the 

 percesocoid and acanthopterygian types; furthermore, Pseudomuffif 

 is a small and obscure form, not ranking either in distribution or 

 importance with Melanotmnia or Rhombatr actus. 



I shall now proceed to give a diagnosis of the family, in which 

 I include five genera — Neoatherina, Pseudomugil, Rhomb" tractns, 

 Aida, and Melanotcenia — which form a very natural group, 

 characterised by the structure of the tirst dorsal fin, the advanced 

 position of the ventrals, &c. 



The metropolis of the family appears to be in north-eastern 

 Australia, where no less than four of the genera have their home; 

 thence it has spread northwards into the rivers of south-eastern 

 New Guinea, westwards to Port Darwin and the Victoria River, 

 south-westwards into the central districts of South Australia, and 

 on, in the aberrant Neoatherina, to Swan River, and finally south- 

 ward to the Richmond and Clarence Rivers District of New 

 South Wales, and perhaps even as far as the Nepean watershed. 



Melanot^niid^. 



Pseudomugilidoi, Kner, Voy. Novara, Fische, p. 275, 1865 {no 

 definition). 



Pseudomugilidce, Kner & Steindachner, Sitzb. Ak. Wiss. "VVien, 

 liv. 1866, p. 372 {no definition). 



Zanteclidce, Castelnau, Proc. Zool. & Acclimat. Soc. Vict. ii. 

 1873, p. 88 (wo definition). 



Neoatherinidce, Castelnau, Res. Fish. Austr. p. 32, 1875 (no 

 definition). 



Melanokeniinoe, Gill, American Naturalist, 1894, p. 708. 



Body rhombofusiform to elongate-oblong, more or less com- 

 pressed. Mouth moderate, terminal, oblique. Two nostrils on each 

 side. Premaxillaries not protractile, forming the entire dentigerous 

 margin of the upper jaw; maxillaries narrow. Gill-openings 

 wide; gill-membranes separate, fi-ee from the isthmus; five or six 



