TIJE AUSTKALIAX .MISECM MAiJAZlXK. 



80 



tlit'in re.^ions ol' Australia. It liddlcs the 

 hanks with its burrows, causiiii;' them to 

 collajist', and is a source of continual 

 trouble to the man on the land. No 

 sooner is a new dam constructed than 

 the presence of this pest is noticed. Per- 

 haps, as has been suiiyested by some, 

 the creature traverses wide tracts of land 

 in the night time from one water- hole 

 to another, or its distribution may very 

 well have been brought about in the 

 manner outlined for the case of I'ara- 

 ti/a. Mr. Charles Hedley, of the Aus- 

 tralian ]\Iuseum, has satisfied himself 

 that the wide dispersion in the Soutli 

 Pacific of certain small invertebrate 

 aninu\ls is due to the agencv of wind- 



blown leaves. He writes as follows: — 

 "Every one who ha,s crossed a woodland 

 track in windy weather has seen hand- 

 fuls of dead leaves whirled up by ed- 

 dying' gusts. Let such a gust pick ui) 

 such leaves from a Pacific atoll, luring 

 the height of a violent cyclone; they 

 tra\el softly, without jarring oft" what 

 has adhered to them, and may easily be 

 dropped on an atoll a hundred miles 

 distant after a few hours. To all col- 

 lectors it is well known wliai numbers 

 of small invertel)rates attach, either as 

 ova, larva or adult, to fallen leaves. So 

 a shower of a few dead leaves might 

 throw at once a dozen species of in- 

 sects, spiders and snails on an island 

 where no life was before." 



Electric Rays. 



r>Y A. R. McCULLOCll. 



Is there any lislierman, professional 

 or amateur, on our coast, who is not 

 acquainted with Electric I? ays, t)r Num- 

 bies as they are sometimes called"? Their 

 extraordinary powers of giving off elec- 

 tric discharges has brought them under 

 the attention of almost every fisherman 

 — sometimes more forcibly than can be 

 remembered with comfort. 



A party of biology students from the 

 Universitv on their annual excur- 

 sion to Port Stephens, recently dis- 

 covered a medium-sized example of the 

 connnon s})ecie:-, II iij))i<tree sub)ugra, 

 m shallow watei'. It burrowed 



beneath the sand with extra- 

 ordinary rapidity when it observed their 

 presence, doubtless realising the pecu- 

 liar incjuisitiveness of such jieople. But 

 all to no avail. One member of the 

 party seized a water-logged stick and 

 connnenced to dig it out, while another, 

 unaware of the identity of the prey, 

 sinudtaneously stabljed it with a feroci- 

 ous looking bowie-knife. Both jumped 

 several feet in the air as they received 

 a violent shock, and very nearly allowed 

 the fish to escape. It was characteris- 

 tically clumsy in its movements, lu)w- 

 ever, and considered its greatest safety 

 lay in seclusion beneath the sand. But 

 the students were not to l)e denied the 



experience of testing its electric proper- 

 ties, so it was soon scooped out onto the 

 beach, where it was prevailed upon to 

 deliver about fifty successive shocks in 

 a space of ten minutes or so. These 

 were finite intense at first, but gradually 

 weakened, and were felt from all parts 

 of the fish, including even the ventral 

 fins and the rim of the snout. An ef- 

 fort to kill the Ilsh by stabbing it sud- 

 denly through the brain produced a pro- 

 nounced discharge which resembled a 

 l)low on the biceps of the stabber, due 

 to the sudden contraction of that muscle. 

 Another investigator, with extra good 

 control of his nerves, retained his hold 

 of a knife while inserting it into the 

 electric organ on the sides of the body, 

 and felt the shock completely through 

 his body from his arm to his feet. When 

 one placed a foot upon the fish a shock 

 was felt m tlie lower muscles of the 

 calf of both legs. 



The electric properties of the numbfish 

 would appear to be merely for protec- 

 tive purposes, since the moutli is so 

 small, and the teeth so feeble, that none 

 but small fishes and crabs are devoured. 

 "Were a shark or other large enemy 

 to seize a numbie, it would doubtless 

 liberate it after the first shock. One 

 could hardly imagine the predicament 



