40 



THE AUSTRALIAN MUSEUM MAGAZINE. 



but often watched small boulders loosen- 

 ed either intentionally or by accident, 

 as tliey l)ounded downwards through the 

 air hundreds of feet at a time, and 

 crashed through the vegetation below. 



From the time one leaves the sand- 

 stone of the lower-lying parts of the 

 island, the whole journey to the hills 

 and back lies over basalt boulders, 

 which may be smooth and I'ounded as 

 Avhen worn by water, or j-ough with 

 jagged points. Strong boots are all im- 

 portant, and if their soles be plentifully 

 scattered with heavy nails, one is en- 

 abled to secure a grip upon the stones, 

 which is surprising to those unused to 

 such heavy footwear. 



The site chosen for our camp between 

 the Hills was near the bank of a "run" 

 which either trickles or rages down tlie 

 Erskine Valley, according to the state 

 of the weather. It drops nearly a 

 thousand feet during its short rocky 

 course of about half a mile, and tu)n- 

 bles over faces some fifty feet high and 

 so precipitous that we could not scale 

 them; occasionally it runs undei'ground 

 out of sight. Yet every pool in its 

 course is the home of numbers of a 

 small shrimp (Xiphocaris), some tiny 

 crabs {Hi/menosoma), and small eels 

 (Anf/uiUa). How they ever reached the 

 height of our camp, about 700 feet up, 

 is a mystery. The eels perhaps utilised 

 opportunities to skirt the faces af- 

 forded V)v extra wet weather, when 

 water luns over most of tlie steeply 

 slojiing hill-sides. We had evidence of 

 their ]>owers of travelling over the land 

 when collecting some on the lower levels; 

 when thrown out onto the bank of a 

 creek, they wriggled through tlie dry 

 grass and fallen leaves as effectively as 

 would any snake. But the slirimps and 

 crabs could scarcely travel in this way, 

 and they could not possil)ly have so 

 reached the streams uj)on the top of 

 Mount Gower where we found them. 



FIJKSH-WATER CHA15 {H ijmenosoma ) . 



This tiny crab is one of tlie most mys- 

 t lions residents of I he islaml. It lives 

 under the stones in the several streams 

 anywhere from sea-level, as in the Big 

 Creek, to the mountain tops. It ]ilays 

 "possum" when disturbed, and as l)otli 



the form and colour of its flat back 

 cause it to closely resemble a small peb- 

 ble, it is very easily overlooked. As Hy- 

 menosoma lacustris, it was first recog- 

 nised from New Zealand, and was re- 

 garded as of interest chiefly because it 

 was the only fresh-water representative 

 of a common marine genus. Later it 

 W'as recognised from land-locked lakes 

 in A^ictoria, and afterwards from Lord 

 Howe Island and Norfolk Island, to- 

 gether with its associate, the fresh- 

 water shrimp Xiphocaris. 



How come these two to appear in the 

 fresh-waters of such widely separated 

 localities? It might be supposed that 

 they spend some of tlieir earlier stages 

 in the sea, as do the eels, and that odd 

 individuals have occasionally drifted 

 from one locality to another; but this 

 suggestion is discounted by the fact that 

 they occur in land-locked lakes and on 

 the top of Mt. Gower, to which access 

 from the sea is impossible. To suggest 

 that the crab and the shrimp are sur- 

 vivors of an ancient fauna which passed 

 from one place to another by means of 

 old land-connections, long since disap- 

 peared, is equally unsatisfactory, for 

 wlio can suppose that Norfolk Island 

 and Victoria, for example, have ever 

 been connected by even the most tor- 

 tuous of land bridges? That the eggs 

 have been transported upon the feet of 

 wading-birds is open to the same objec- 

 tion as the proposition that they have 

 been wdnd-borne, an ol)jeetion based 

 upon the belief that such eggs would be- 

 come dry and wither during their pass- 

 age. But this is mere conjecture, and 

 whatever be the explanation of tlie oc- 

 currence of these two crustaceans in 

 fresh-waters so widely separated, it will 

 form a chajiter of fascinating interest. 



THE SUMMIT OF ilOUNT GOWER. 



The top of Mount Gower is very dif- 

 ferent from that of Mount Lidgbird, be- 

 ing a comparatively flat ai-ea several 

 hundred acres in extent. Two "runs" 

 converge and disappear over the sheer 

 cliffs, falling perhaps a thousand feet 

 into the Erskine Valley, the water trick- 

 ling down them being supplied direct 

 from the clouds which so commonly en- 

 velop the mountain tops. This area 



