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Rh greater subdivision and the multiplication of genera. No criterion 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 throughout this work I have avoided using that term. My reason for this is that, although the word “species,” as now generally understood, 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 representative—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 Möller 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. R. 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