240 JOURNAL, BOMBAY NATURAL HJSTORY SOCLETY, Vol XI. 



Darjeeiing- district 'west of the Teesta river. The late Mr. Otto Moller 

 observed these same limits for the zoological definition of the country. 



Bhutan. — This country is less known and. more inaccessible than 

 Sikhim ; its fauna has, in consequence, not been worked at to the same 

 extent. It is bounded on the north by Thibet, on the south by the Bengal 

 and Assam Duars, on the east by an undefined line separating it from 

 the independent tribes of the northern Assam Himalayas, and on the 

 west by Thibet (Amo Chu or Chumbi Valley), the spur from Gipmochi 

 to Richi-la, thence along the Darjeeling boundary as far as the junction 

 of the Sip Chu with the Jaldacca river. Again, by reason of the eli - 

 matic similarity of the adjoining portion of the Darjeeling district, 

 known as the Daling Division, I include the same under the name of 

 Bhutan, of which, previous to 1866, it formed a part. 



The physical features of Bhutan are widely ditferent from those of 

 Sikhim; the hills rise more abruptly from the plains, a chain of hills be- 

 tween 6,000 and 10,000 feet being situated less than ten miles from the 

 same, whereas over 15 miles of lower hills intervene in Sikhim between 

 the first ridge of the same height and the plains. The rainfall on the 

 outer spurs of -Bhutan is far greater than on those of Sikhim. Roughly 

 speaking, the annual average from the Sikhim Terai to the Ghoom- 

 Darjeeling ridge is from 120 to 200 inches, and from the Bhutan-Duars 

 to the Richi-la spur it ranges from 200 to 300 inches. In the inner 

 valleys the rainfall is much smaller : that for example of the Rungeet 

 Valley at certain places averages only about 60 inches annually. Among 

 Rhopalocera many species which are found rarely in Sikhim may be 

 met with quite commonly in Bhutan, and in the Heterocera Bhutan 

 seems to surpass Sikhim in quantity of species, although, of the inde- 

 pendent territory, as yet only the outer spurs have been worked. 



Dr. Waddell, in his " Birds of Sikhim " (" Gazetteer of Sikhim," 

 Risley), divides the country into five zones, which might be found 

 applicable to the Heterocera of Sikhim and Bhutan also. His divisions 

 are : — ■-- > 



I. 'Tropical 125— 2,000 feet above sea-level. - 



II. Subtropical 2,000— 5,000 „ „ „ „ 



III. Temperate 5,000—9,000 „ 



IV. Subalpine 9,000—13,000 „ „ „ „ 

 V. Alpine 13,000—17,000 „ „ „ „ 



