INTRODUCTION. XU1 



greater subdivision and the multiplication of genera. No cri- 

 terion exists as to what are generic characters, and as there does 

 not seem to me that any greater convenience is gained by this 

 minute subdivision, I have preferred to arrange the forms under 

 large and comprehensive genera. 



With regard to species, it may perhaps be noticed that through- 

 out this work I have avoided using that term. My reason for 

 this is that, although the word " species," as now generally under- 

 stood, is not likely to be entirely misinterpreted, the evil 

 connotations of pre-Darwinian times still cling to it, and to many, 

 perhaps unconsciously, convey the idea of fixity. The term 

 "form,"' on the other hand, though not entirely satisfactory, 

 at any rate implies the possibility of change. That forms are 

 constantly but slowly changing is a fact that is emphasized by 

 every increase to our knowledge of living things. It is strikingly 

 apparent in the Lepidoptera, of which Dr. D. Sharp says : " A great 

 deal of evidence, both direct and indirect, has accumulated 

 showing that the organization of many Lepidoptera is excessively 

 sensitive, so that slight changes of condition produce remarkable 

 results." The system of regarding local representatives of typical 

 forms as of equal rank to them seems to me unsatisfactory, as 

 all connection between the two forms is ignored. It is true 

 that in the present state of our knowledge it is often a matter of 

 conjecture as to which is the typical form and which the race, but 

 in my opinion it is of great importance to draw attention to the 

 extremely close relationship existing between many forms, so as 

 to facilitate the tracing-out of the connection between them. In 

 this work, purely as a matter of convenience, the form first 

 described is made the type, its geographically limited repre- 

 sentative — differing perhaps very slightly, but constantly — the 

 race ; but it must be clearly understood that in many cases the 

 reverse is quite as likely to be the truth. 



In conclusion, my best thanks are due to the many who have 

 aided me by the gift or loan of specimens. From Sikhim my 

 friend Mr. Fritz Moller has sent me large collections in the most 

 perfect condition. Many of the forms in these were procured at 

 high altitudes, and are most interesting and rare. To Col. E. E. 

 Johnson, late of the Indian Medical Service, I owe the gift of a 

 small but very valuable collection from Simla and from Shillong in 

 Assam. To Col. Swinhoe I am indebted, not only for the gift of 

 many specimens, but for the privilege of examining at leisure the 

 fine series of Indo-Malayan forms contained in his collection. 

 Mr. Gilbert Eogers, of the Imperial Forest Service of India, in 

 the most lavish way, employed native collectors in the Andaman 

 and Nicobar Islands, and has generously placed the material 



