POST LARVAL STAGES OF AUSTRALIAN FISHES. 
145 
1944 have produced planktonic stages comparable in development to those 
described by Tosh. In addition, this source yielded many postlarvae inter- 
mediate in size and development between these and the smallest fry that have 
been seine netted in the sandy shallows of the same estuary. A selected series 
of such stages is depicted in text fig. 5 and is of particular interest in exhibiting 
development of the fin-rays and the transition of pigmentation from the simple 
larval pattern to the dorsal blotching, characteristic of the younger age-groups 
of this species. 
According to Tosh (1902) the spawning season in Moreton Bay 
(Southport) is September to February. Larvae and postlarvae ranging in 
size from 1-5 to 8-0 millimetres and recognisable as those of S. ciliata appeared 
in the Noosa River plankton first in September. Slightly larger planktonic 
postlarvae (11-0 mm.) were taken in October and again in December. The 
smallest Sand Whiting caught in the seine net measured 15-5 millimetres. 
Postlarvae of sizes less than 20-0 millimetres have been seined at Caloundra 
and Noosa River in June, September, October, November and January. Fry 
measuring 30-0 millimetres have been collected similarly from April onwards. 
Apparently the spawning period is an extended one, but the planktonic phase 
appears to be restricted mainly to early summer and for each individual it 
terminates when a size of about 15-5 millimetres has been reached. 
Planktonic larvae less than 5-0 millimetres in size (text fig. 5A), although 
possessing a well-developed mouth and with complete absorption of the yolk 
material, have yet to differentiate their fin rays. The black pigment is arranged 
in a single ventral series extending from the region of the heart posteriorly 
to the tail region. There are usually about eight cells anterior to the anus and 
rather less chromatophores than caudal myotomes in the post-anal region. There 
are one or two isolated cells on the dorsal border of the caudal region. 
In larvae of 6-5 millimetres (text fig. 5B) the rudiments of the rays of 
the dorsal, anal and caudal fins are well differentiated. The black chromato- 
phores of the ventral series persist from earlier stages but the dorsal series 
has increased in number and extends further forward basally along the second 
dorsal fin. 
At 10-5 millimetres (text fig. 5C) all fins and their radial components 
are well defined. The number of rays are easily counted, making it possible 
to identify these larvae specifically as S. ciliata rather than S. macutata . They 
possess the characteristic modal fin formula: D. XI. I, 17; A. I, 18; P. 15. 
The black chromatophores are greatly enlarged and stellate. The ventral series 
still persists along the gut and extends past the anus along the ventral border 
of the caudal somites. There is a large chromatophore at the base of each anal 
fin-ray. The dorsal series is restricted to the areas at the bases of the fins and 
the chromatophores have increased in number and are arranged in groups. A 
third series has made its appearance along the mid-line of each side of the body. 
These post-larvae are still planktonic. 
Upon reaching a size of 15*5 millimetres (text fig. 5D), namely the stage 
when the habit is altered from planktonic to littoral, the tiny Sand Whiting 
begins to acquire the shape and general facies of the adults of its species and 
