358 L. de Niceville & Dr. L. Martin— Butterflies of Sumatra. [No. 3, 



and western borders of these sultanates are formed by the Barisans, 

 here named the Battak mountains from the inhabitants of these ranges 

 being several tribes of anthropophagous Battaks, the aborigines of 

 Sumatra. The different ranges of the Battak mountains here include 

 the extensive Toba highlands, which surround the large and for long 

 mysterious Lake Toba that lies in their centre. North of this lake 

 is the Karo plateau, inhabited by the Karo-Battak tribe, and forming 

 the true " hinter-land " of the above-named sultanates. The northern 

 boundary of this region — as Ave deal chiefly with this pai^t of the island, 

 we will call it " our area " — is the mountainous land of the Gayoe 

 and Alias tribes, who are Mahomedans ; to the east lies the large 

 sultanate of Siak. The altitude of the Karo plateau may be estimated 

 at about 4,000 feet ; the highest peaks of the Battak mountains are 

 Simanabum, nearly 8,000 feet in height, and Sebayak, which is a little 

 over 7,000 feet. 



Owing to its situation, protected on the south and west by the 

 Barisans, and with the narrow and quiet Strait of Malacca, beyond 

 which again is the Malay Peninsula also with a high central range 

 to the north and east, there is no monsoon in our area, and consequently 

 neither a true rainy, nor a true dry season ; though during the 

 .south-west monsoon there is a little more rain than usual, say about 

 18 days in the month, while during the north-east monsoon there are 

 only 11 rainy days in the month. Nevertheless there is a yearly average 

 rainfall of about 90 inches (2,200 mm.) ; this, together with a 

 mean daily temperature of 80°, and an extreme daily range of 126° 

 Fahrenheit, makes a very damp and unhealthy climate, but fits it for a 

 high development of insect life. The plains of the three sultanates, 

 the outer ranges of the Battak mountains, and the Battak mountains 

 themselves, which include the Karo Central Plateau, are the localities 

 where all the species of Rhopalocera contained in our collections and 

 enumerated in the following list, have been captured, except a few 

 from the Gayoe lands and from Indragiri, another Malayan sultanate 

 south of Siak, and nearly opposite to Singapore. 



The plains were formerly entirely covered with large, dense, lofty 

 primeval forest, but this has had to make way for the miserable tobacco 

 plant, of which the cultivation began about the year 1865. The 

 primeval forest once destroyed by fire and the axe does not grow again, 

 but is replaced by a high-growing and tenacious species of grass, 

 called " Lalang " in Malay (Impcrata arundiiiacea, Cyrill.), which 

 now entirely covers all the ground temporarily unoccupied by tobacco. 

 The cultivation of the nicotinous plant pays so highly and yearly 

 so increases in extent, that there is now no forest whatever left in the 



