HETEROCERA OF SIKH IM AND BHUTAN. 241 



In the first zone, those forms which are met -with in the plains abound 

 together with a few endemic species ; in the second, the forest trees 

 become covered with lichens and mosses, and those species which feed 

 in the larva stage on them, are found here ; the third zone, which is 

 enveloped for nearly six months in mist and clouds, seems particularly 

 favourable to Heterocera ; the fourth has but a short season suited 

 to insect life ; and, the fifth, which ranges from above the tree limit to 

 the limit of perpetual snow, has not been worked at to a great extent : 

 it however can scarcely be expected to yield many species. The 

 following table will show, as nearly as may be, where the different 

 families or subfamilies of the Heterocera may be met with, although 

 a few of nearly all may be found outside the limits given. In the case 

 of any family not being mentioned, it must be understood that it is not 

 confined to any particular zone. 



Tropical.- — Quadrifince, Deltoidince, Focillince, Uypsidce, Agafi- 



stidce, Thyrididce^ Pyralidce. 

 Tropical and Subtropical. — Epiplemidce^ Uraniidce, Acontiinai, 



Drepanulidce, Lymantriidce, Limacodidce, Psy- 



cliidce, Epicopiidce, Eupterotidce, Sesiidce, Zygce- 



nidce, Nolince. 

 Subtropical and Temperate. — Lithosiince, Trifince, Noio- 



donlidce. 

 Temperate and Subalpine. — Arctiidce, Cymatoplioridce^ Geo- 



metridce. 



In the accompanying map the names of the chief places in Sikhim 

 and Bhutan, also the courses of the chief rivers, are shown. 



It is impossible to give the names of any places within Independent 

 Bhutan to which native collectors have penetrated, as the inhabitants 

 being very disinclined to allow intrusion, the collectors employed 

 have given them a wide berth, so as to avoid being interfered 

 with, and consequently have not heard the names of the localities they 

 have visited. By far the greater proportion of moths recorded from 

 Bhutan in this catalogue have been obtained in the Daling Division 

 of Darjeeling, or as it is sometimes called, British Bhutan. 



The numbers given to the species are taken from Sir George 

 Hampson's work, so that they may be referred to without difficulty. 



