POST LARVAL STAGES OF AUSTRALIAN FISHES. 
137 
until they attain a length of approximately 12 millimetres. Such larvae have been 
collected in tow nets in the Noosa River during March 1944 and June 1940 
and in Bribie Passage (Caloundra) during March 1944. It has been observed 
in both these estuaries that, upon reaching this size, these Bream fry leave the 
plankton and congregate, along with those of the related Austrosparus sarba 
and other species, amongst the Zostera weed growth of shallow flats and brackish 
creeks within a mile or so of the respective river mouths. Similar nursery 
grounds have been observed near the mouths of the Bellinger River, Nambucca 
River and Lake Macquarie. This change of habitat coincides with the first 
indication of development of sub-adult pigmentation. 
Bream larvae and postlarvae smaller than 12 millimetres are wholly 
transparent and are characteristically marked with distinctive series of black 
chromatophores. There is probably some yellowish pigment, but this has not 
been observed in the formalin preserved specimens used in the present study. 
In a typical planktonic postlarva of length 10*5 millimetres as is illustrated 
in text fig. 1A, the black chromatophores form three series, namely: a cluster 
on the postero-dorsal aspect of the head ; a longitudinal series following the 
ventral margin of the caudal somites, mainly at the bases of the anal and caudal 
fins; an internal cluster lining the visceral cavity postero-dorsally. In post- 
larvae of this size, the head length is approximately 4 and the greatest body 
height 4J in the total body length. The eye diameter is slightly greater than 
the snout length and is 3 in the head length. 
The smallest Bream collected in the seine net measured 12-5 millimetres 
and is illustrated in text fig. IB. Its pigmentation indicates the beginning 
of the transition from planktonic to littoral habitat. The sparse black pigmen- 
tation characteristic of planktonic facies is being masked by a proliferation 
of chromatophores constituting the rudiments of a pattern of light and dark 
banding which is destined to persist throughout the first year of life. The 
nature of this change is parallel to that shown to take place in various 
Mediterranean species of Sparidae by Ranzi (1933) and in the American Scup 
by Kuntz and Radcliffe (1917). Bream postlarvae of 12 millimetres and over 
show a progressive development of blackish brown Y-shaped vertical bands on 
the dorsal half of the body, superimposed upon a general ground coloration 
of greenish bronze. About six or eight of these bands appear and they are 
alternately broad and narrow. Small Bream differ from small Tarwhine 
( A . sarba ) in the pattern of banding, the latter species possessing five or six 
approximately equal and broader bands which extend ventrally below the level 
of the mid-line. The cephalic series of black chromatophores of the planktonic 
postlarvae are substituted by paired clusters overlying the hind brain on the 
postero-dorsal region of the head. These are characteristic in that they are 
relatively less distinct than those of the Tarwhine. At 16-0 millimetres the 
first rudiments of scales are noticeable, each scale being outlined on its ctenoid 
margin by a semi-circle of pigment dots. These are noticeable in the caudal 
region of the specimen depicted in text fig. 1C. At 18-0 millimetres a complete 
coat of scales is discernible. At this stage of development the lateral line is 
marked off by its relatively darker pigmentation. Increase of brownish pigment 
on the scales gives the appearance of a parallel series of longitudinal brownish 
