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Show " of the individual life becomes greater, a proportionately smaller " number of generations will succeed one another in a given time, " and therefore the rate of change that the stock will undergo will " be lowered. The same cause may have brought about the ex- " tinction of many of the bulky, highly specialized, and presumably " slow-breeding groups of animals, such as the Titanotlieres, which " have been unable to undergo sufficiently rapid modification " to enable them to keep in harmony with a changing en- " vironment." 230 MR. R. SHELFORD OX MIMETIC INSECTS AND [Nov. 4, The following papers were read 1. Observations on some Mimetic Insects and Spiders from Borneo and Singapore. By R. S h e l f o r d , M.A., C.M.Z.S., Curator of the Sarawak Museum. With Appendices containing Descriptions of new Species by R. S h e l f o r d , Dr. K a r l J o r d a n , C. J . G a h a n , the Rev. II. S . G o r h a m , and Dr. A. S e n n a . [Received November 13, 1901.] (Plates X IX .-X X II I.1) The theory of mimicry having originated and having been further elaborated chiefly from a study of South American insects, it is but natural that these should figure largely in all works relating to the subject. This paper, a brief abstract of which, arranged by Professor Poulton, appeared in the British Association Reports, 1900, p. 795, is an attempt to bring into greater notice the richness of the Malayan sub-region in similar mimetic species-nearly all the examples here described and discussed having been captured within the last four years in a circumscribed area of 10 mile radius, with Kuching, the capital of Sarawak, as its centre. A recent collecting-trip of three weeks' duration to Mt. Penrissen (about 50 miles inland) was productive of several new examples; and I feel convinced that a similar reward awaits the collector on other mountains of the island and on those of Sumatra, Celebes, and other numerous islands of the great Archipelago, many of which are still virgin ground to the entomologist. In order to summarize as much as possible our knowledge of the mimetic insects of Borneo, I have drawn up tables of the mimetic Longicorn Beetles and of the Lepidoptera; the latter is a modification of a somewhat similar list given by Haase in his ‘ Researches on Mimicry' (English translation), Stuttgart, 1896, but I have found it necessary to question certain conclusions and to make a few additions. 1 For explanation of the Plates, see page 281. |