48 



TIIF. MIGRATION OF THF, jni.I.Y-TAIT. OR EFX-GUDGEON, GdloXiaS attetlUatUS. 



Two barriers of cheesecloth were fastened across the stream, being placed so that tliev allowed 

 the water to pass through, but blocked the passage of fish either up or down stream. When first 

 arranged in position both barriers were wholly in fresh water, and a careful search for hall an hour 

 failed to discover any fish above, below, or between them ; the conditions for searching were particu- 

 larly good, the water being quite clear and running over white sand, and we could hardly have tailed 

 to find the fish had they been present. After hall an hour the tide rose sufficiently to send an extra 

 big wave over the lower barrier(d) and we immediatelj afterwards secured a fish above it ; successive 

 waves produced further specimens until the lower barrier was destroyed. While we «en- getting 

 fish at the lower barrier, the upper one (i) was also carefully watched, but we failed to find any fish 

 above it; after tin- lower one was destroyed, however, we found several specimens directly below 

 the barrier (6) and swimming stoutly against the strong current of the stream passing through it. 



This test was carefully and successfully carried out, and seems to leave no doubt that the fish 

 entered the stream through the surf from the sea, and were making their way upstream. We have, 

 therefore, to assume that they had been bred in the sea. where they had undergone their earlier 

 development; they had possibly been carried far from the place of their birth l>v the currenl 

 extending along the coast; ami, finally, they must have been remarkably sensitive to the presence 

 of fresh water to discover so small a stream as that in which they were found. 



There have been several records of other species of Galaxias occurring in the sea, and it appears 

 I ml able that (/. truttaceus is not confined to fresh water ; it occurs in both Victoria and Tasmani I 

 and I ha\e recently examined specimens from Albany, south-western Australia. Numerous fresh- 

 water animals are common to the northern Tasmanian and Victorian rivers, and are generally supposed 

 t<> have crossed Mass Strait when that area was elevated above the sea ; no such explanation can 

 account for tin- preseni e oi '/. iruitaceus in south-western Australia, however, and it is more probable 

 tli.it it reached there by way oi the sea while in its larval stages. 



The following is a description of the larval specimens collected : — 



Body cylindrical anteriorly, becoming compressed posteriorly, deepest above the vent. In a 

 specimen 38 mm. long, including the caudal tin, the depth is 11.7 in the total length and 1.5 in the 



1 1 which is ,-.(1 in the length. The dorsal tin begins either slightly 111 advance of or a little behind 



Hie verticle of the anal. Ventrals almost midway between the operculum and the vent. Dorsal- 

 with ten. anal with fifteen complete rays, the last being divided 111 each fin ; caudal with sixteen, 

 pectoral with about thirteen ravs. 



In life the body was quite transparent, with deep black pigment spots scintillating with opal- 

 escent colours. They are large and symmetrically disposed on the head, there being one or two on 

 the supero anterior portion of the snout, and one on each side enclosing the nostrils, another between 

 tin eyes, and three on the occiput forming a triangle of which tin- base is forward ; t.vo more behind 



these coalesce to ci :nce a median sni.s extending along the vertebral column. The lips are 



black, and there an- several larger and smaller spots on the opercles ; a broad curved spot on the 

 body below the opercular margin. Eyes black above, iris silver. Vertebral column defined by a 

 row of black spots ; one spot marks each vertebra, and I counted sixty-three in two specimens, the 

 last being turned upwards. On each side of the column is another row on the outer surface ol the 

 body. A row of spots extends along each side of the alimentary canal in a straight line from the 

 !.i e ol the pectoral to the vent. Finally, paired rows of spots are present at the bases oi the dorsal 

 and anal fins which extend backward to the base of the caudal. Caudal rays blackish, the others 

 transparent. 



