128 A NEW FAMILY OF AUSTRALIAN FISHES, 



The above remarks will, however, suffice to show how diverse 

 the views of authors have been as to the position which these 

 fishes and their allies are entitled to hold in the ichthyological 

 system. 



A I DA. 



Aida, Castelnau, Res. Fish. Austr. p. 10, 1875. 



Body very compressed; upper part of the head unequal : opening 

 of the mouth very oblique, almost perpendicular; opercle and 

 preopercle without teeth or spines, the first with a double edge. 

 Teeth fine, minute, disposed on one line; two very feeble canine 

 teeth in front of the upper jaw; a transverse line of teeth on the 

 palate. Two dorsal fins, the first composed of five spines, the 

 four last prolonged; the second with one spine and thirteen rays, 

 which increase in length backwards : anal with two sj^ines and 

 se"\enteen rays, formed like the second dorsal : ventrals inserted 

 behind the pectorals and united at their base, formed of one spine 

 and five rays : pectorals placed at about half the height of the 

 body, rather small: caudal bilobed. Scales rather large and entire 

 on their edges, the posterior part of the head and the opercle 

 covered with scales similar to those of the body; no lateral line. 

 (Castehiau).* 



Etymology:— unknown. 



Type : — A ida inornaia, Castelnau. 



Distribvition : — Gulf of Carpentaria. 



If an analysis be made of the differences between the 

 above description and that of Jihombutractns, it will be found 

 that they are but slight and such as, bearing in mind the care- 



• With the exception of rearranging the sequence of the sentences and 

 of omitting some unnecessary words no change has been made ii. 

 Ci.stelnau's own phraseology; and these transpositions have been under- 

 taken merely to bring the above diagnosis into sequential accordance witli 

 that uf lihomhatractus, and so make the comparison of the two genera 

 easier for those who follow me in tiie study of these interesting forms. 



