132 MEMOIRS OF THE QUEENSLAND MUSEUM. 



Uses: — Naturally with a fish wliich is so scarce in our seas we have no 

 data as to its edible qualities, but there is no reason to believe that it differs 

 in any respect from its congeners, of one of which, the Western Atlantic A. hians, 

 we learn from Valenciennes on the authority of Poey that ' ' it is good eating. ' ' 



Range: — East Coast of Australia. Moreton Bay {Ogilhy) ; Port Stephens 

 (Stead). 



Dimensions : — To at least 600 millim. 



Illustration: — Miss Clarke's beautiful figure is taken from the Moreton 

 Bay specimen previously referred to. 



Part V.— HETEROSOMATA (No. 1). 

 Order HETEROSOMATA. 



''THE FLAT-FISHES." 



No one who with open eyes regards the works of Nature, which encompass 

 him on every side in such prodigal profusion, can have failed to notice the want 

 of symmetry which, through having both eyes situated on the same side of the 

 head, characterizes these fishes in the adult state. Except during the earliest 

 stage of their existence the flat-fishes lie at the bottom, when quiescent, on one 

 or the other side, which may be right or left according to the family to which 

 the individual belongs; for an obvious reason these sides are technically termed 

 "eyed" or "blind." The eyed side is invariably colored owing to its exposure 

 to the light, while the blind side, being turned downwards and, therefore, not 

 affected by the rays of the sun, is normally colorless. Exceptions, however, 

 occur to both these laws, for it is not unconnnon to find reversed examples 

 among all forms of flat-fishes, so that a normally "dextral" species— that is a 

 species having the eyes on the right side — becomes individually "sinistral" — 

 having the eyes on the left side — and vice versa ; specimens too are occasionally 

 taken, which are more or less fully colored on both sides. Indeed it is well 

 known that certain species, among them our "Queensland Halibut" (Psettodes 

 eriimei) are dextral or sinistral in about equal numbers. It is probable that 

 the species, which exhibit this divergence from the common law in a more marked 

 degree, are more directly descended from their percoid ancestry, than those 

 which have developed a more constant dextrality or sinistrality. 



For many years it has been known that the young flat-fish, on its 

 emergence from the ovum, has the eyes, like those of other fishes, placed 

 symmetrically on the opposite sides of the head, and that at this period the 

 body assumes a vertical position when the fish has occasion to move from place 

 to place. At a very early age, however, one eye is forced round the dorsal 

 surface of the head, and thenceforward becomes the upper eye, as distinguished 

 from the lower, in which no such compulsory migration has taken place. The 

 relationship of the eyes to one another, both as to size and position, varies 

 greatly in the different genera, and when taking the proportionate measurements 

 of the eye to the head, or more specially to the snout, it is preferable to utilize 

 the lower eye, as being, from its immobility, the more constant. It is to this 

 compulsory migration of an eye that the asj^mmetry of the frontal bones among 



