6i 



in larger, sometimes in smaller numbers, in proportion to the more or less 

 advanced stage in the evolutionary process. It has also been said that the 

 colour of the upper-side of the front part of the hind-wings, where the 

 scent-glands are, should be greyish violet in T. Hecabe L., but rose-coloured 

 in T. SiLHETANA Wall., indeed a very subjective characteristic, from which no 

 difference of species can be deduced. According to a note of Watson in 

 Journ. Bombay Soc. 1896 the caterpillar of T. Silhetana Wall has a black 

 head and lives gregariously, whereas that of T. Hecabe L. has a green 

 head and lives solitarily, according to my observations, however, it is the 

 caterpillar of T. Hecabe L. which has, generally at least, a black head and 

 which undeniably lives sociably, sometimes even in such numbers together that 

 it becomes destructive. The caterpillar of T. Sari Horsf., on the contrary, 

 has a green head. Always at his hobby, but not in consequence of serious 

 observation, De Niceville pretends that the specimens of T. Silhetana Wall., 

 which have the apex of the fore-wings on the under-side marked with brown, 

 should represent the form of the dry season! 



The caterpillars generally live together on the same plant; they may often 

 be seen sitting close together on the stem of a leaf, which has been eaten. 

 They are very common on the leaves of the tree which is called bilalaiig at 

 Batavia, but joiiar (Cassia Florida Vahl) elsewhere, and also on the touri 

 (Agati Grandiflora Desv.), the jengkol (Pithecolobeum Bigeminum Mrt.), the 

 koupang (perhaps Macrotropis Sumatrana Miq.), the kajoic gabous (Alstonia 

 Scholaris R. B. R.), \ki^ petek (Parkia spec), the daivon klitji, called in Sundanese 

 mata hiang (Guilandina Bonduc L.), and on plants called kajou wangkal and 

 katok, as I have been told. In June 1894 they appeared in such numbers at 

 Buitenzorg on the ketimour (Albizzia Moluccana Miq.) that they were distruc- 

 tive. This polyphagy is probably one of the reasons why this species is so 

 common and is so widely spread. It is also evidently an animal with a strong 

 power of assimilation ; in the middle of the dry season when it had not rained 

 for more than six weeks at Batavia, a whole nest of such caterpillars on jengkol 

 leaves was brought to me. Its colour is generally greenish yellow in many 

 shades up to real green, with a more or less bright yellow streak on the sides, 

 while the transparency of the back makes the dorsal vessel appear like a dark 

 dorsal line. The body looks like shagreen and seems sometimes to be covered 

 with small bluish grey or black spots; when magnified this proves to be caused 

 by some parallel folds in the skin of each segment, which folds bear small 

 black spines, the tops of which show like the said spots. Sometimes we see 

 at the top of each spine a small bubble. On the back and the sides a few white 

 hairs protrude. The head is sometimes, but not always strongly notched on 



