XXV 



bent backwards all the same, the girdle-thread would necessarily be stretched 

 so tightl)-, that the pupa must be crushed to death. Hence a very ingenious 

 precautionary measure, very much analogous to the one spoken of above. 



According to the observations of Mr. van Deventer it seems that this 

 species always attaches its pupa to the under-side of leaves, a circumstance 

 which would render the measure in question still more necessary, because a 

 bamboo-leaf, when drying up curls inwards and would thus stretch the girdle- 

 thread in the above mentioned disastrous manner. Later observations must 

 settle the question whether this larva always takes this measure of precaution, 

 also when it is going to pupate on a leaf of one of its other feeding-plants, 

 which is not so inclined to bend inwards as that of the bamboo. 



Of this monograph, soo, the systematism is from the hand of Mr. P. C. T. 

 Snellen ; especially with respect to this difficult family this required much 

 labour. The latest system, that of P. Mabille, published in 1 903 by P. Wytsman 

 in his monograph on this family in Genera Insectoruiii, has been followed here, 

 though in connection with the identification of some species Snellen does not 

 always agree with the opinion of Mabille. 



Besides the papers quoted, use has also been made of the paper of C. Swinhoe 

 published in the Trans, of the Ent. Soc. of London igo8. ''On the species of 

 Hesperidae from the Indo-Malayan and African Regions described by Heir Plotz, 

 ivith description of some neiv species." Then almost all the numerous figures of 

 imagines have again been made under his direction and at his own expense. 

 Mr. Fruhstorfer has been so kind to have seven species, wanting in our 

 collection, designed for me by Mr. J. Culd at Geneva, after specimens from 

 his own collection. This Lepidopterologist has also in general kindly assisted 

 me in this labovir ; an assistance so very valuable also for this reason, that of 

 those specimens which Mr. Fruhstorfer says that originate from Java, I 

 consider this habitat as certain; a confidence that I dare to place only in very 

 few such statements. For not a few butterflies in European collections are 

 said to originate from Java, though in reality they are not from that island, 

 but have been gathered on other islands of the Indian Archipelago and only 

 transported via Java to Europe. All figures of the earliest stages were made 

 in Java during my stay there, as was the case with the Pieridae. 



With regard to the scientific names of plants, the same plan has been followed 



as that explained in the Introduction of the study of the Pieridae. It only 



remains to refer to a new work published in 1909, viz. Nieiitv Plantkundig 



Woordenboek voor Ahderlandsch Indie, the production of a scientific collaboration 



of a ver}' competent botanist with a no less competent connoisseur of native 



