HOUTMAN ABEOLHOS ISLANDS. 159 



currents and wave action. In the latter case small islets are formed and are 

 often capped with a little sand. They only rise perhaps one foot above high- 

 tide mark and are known by the fishermen as " Sandy Islands." 



The Fauna of the Wallaby Group. 



The name of the group suggests the first member of the fauna that 

 deserves mention. The Wallaby Macropus eugenii, Desm., occurs on both 

 East and West Wallaby Islands and in very large numbers, especially on the 

 West Wallaby Island. I have seen far more individuals in one afternoon at 

 these islands than of all species of marsupials seen on the mainland in three 

 years ! Some surprise was exhibited last year when I stated that four were 

 shot on our first expedition without moving from the one place — one shot 

 having killed two. On our second expedition we beat this by actually 

 catching four specimens alive, by merely running them down ! It is no 

 uncommon sight to see half a dozen leaping before one at the same time. 

 Naturally it is a point of the greatest interest to find fifty miles away from the 

 coast, on a small coral island with only halophytic bushes, an animal of this 

 kind in such large numbers. The large Wallaby Islands are the only ones 

 inhabited by a marsupial. Traces of other mammals also occur, and a much 

 decomposed rat was found (and left) in one of the water-holes on West 

 Wallaby Island. Reptiles abound on these islands and were even common on 

 the smaller ones which we have already referred to as rising from the 

 Wallaby Reef flat. One of the most interesting is the Carpet Snake 

 (Python spilotes), which occurs in very large numbers on West Wallaby 

 Island. We could hardly ever walk down the two miles of the old guano 

 tramway on the occasion of our first expedition without meeting several 

 specimens lying across it, and usually they averaged about 7 feet in length. 

 They were very sluggish. Curiously enough we did not see one in 1915 ; 

 probably they hibernate in winter, and the winter of 1915 was particularly 

 severe and extended well into October. No specimens were met with on 

 any other but the West Wallaby Island. Two other species of snakes are 

 supposed to occur in the Wallaby Isles, one of which was seen but not 

 captured. Reference to the Lacertilia will be made in Mr. Alexander's 

 paper on the Vertebrates. Seventeen species are recorded altogether from 

 the Abrolhos Isiands, and probably most of these occur only on the West 

 and East Wallaby Islands. Two or three species are common on the smaller 

 islands of this group, but the larger southern islands of the Pelsart and 

 Easter groups have only one or two. Two species of Amphibia, frogs, are 

 recorded from the islands, but we were unsuccessful on both occasions 

 in finding any. On our second expedition we thought we should be more 

 successful owing to the wet winter and our earlier arrival at the islands. 

 We failed, however, to see any trace of them. 



LINN. JOURN. — ZOOLOGY, VOL. XXXIV. 12 



