289 



THE GEOGRAPHICAL DISTRIBUTION OF THE 

 MOTHS OF THE SUBFAMILY BISTONINAE. 



J. W. HESLOP HARRISON, D.Sc. 



{Continued from page 194). 



And the only direction left for consideration is that toward 

 Asia. Very tempting is the configuration of the long chain 

 of islands, hinting at continuity at no remote geological period. 

 But between Asia and Australia, almost gossamer-like in its 

 outward appearance, is that narrow strait just east of Java 

 between Bali and Lombok. It is in truth a ' great gulf fixed ' 

 almost impassable for bird, beast, and insect. So few are the 

 forms (they exist of course) which have transgressed this 

 boundary line that the few which did, and now appear as 

 an Indo-Malayan leaven of the Flora and Fauna of New 

 Guinea, Australia, and the Celebes are explicable on the basis 

 of the many accidents that time produces. None are flagrant 

 breaches of our expectations. 



The strait between Bali and I-ombok must be of extra- 

 ordinary age, for it brings back once again to our eyes those 

 early days when Australia was as well off in its plants and 

 animals as the rest of the world. No form is more emphatic 

 in asserting this than the Secondary Cossid genus, Xyleutes, 

 mentioned before, as to it the barrier was non-existent, it 

 occurring in Borneo, India, Ceylon, and the Philipine Islands. 

 Thus nothing can be gained from the East Indies. 



Our search for the desired passage must be directed elsewhere. 

 But where shall we look ? Suggestive land bridges simply 

 do not exist. Still what do the soundings tell ? We see an 

 interesting series of shallows stretcliing from New Zealand, 

 extpnding up to and including New Caledonia where similar 

 shallows, striking tangentially from the coast of New South 

 Wales, meet them. Further, without significant break, these 

 shallows are prolonged via the Caroline, Ladrone and Bonin 

 Islands to the South East of Japan, and we are brought up 

 exactly in the area with which our linkages must be made. 



Note the significance of this line ; it coincides with the 

 Western Pacific Belt of volcanic action, and in addition these 

 islands, in sharp contradistinction with most Pacific Islands, 

 are composed of volcanic rocks in many cases of immense age. 



Of volcanic origin, then, and lying on the line of perpetual 

 volcanic action and seismic disturbances, they must have been 

 prone at any time to excessive uplifting which would produce 

 peninsulas or isthmuses of the Panama or Malay type, down 

 which would pass, as in America, a backbone of lofty mountains 

 of which the rudiments attaining a height of 2,000 feet or even 

 3,000 feet persist to this day. ■ 



1918 Sept. 1. 



