230 MR. R. SHELFORD OX MIMETIC IXSECTS AND [Xov. 4, 



" 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 iindergo will 

 "be lowered. The same cause may have brought about the ex- 

 '• tinction of many of the bulky, highly specialized, and presumably 

 k" slow-breeding groups of animals, such as the Titanotheres, which 

 " have been unable to undergo sufficiently rapid modification 

 " to enable them to keep in harmony with a changing en- 

 " vironment." 



Tlie following papers were read : — 



1. Observations on some Mimetic Insects and Spiders 

 from Borneo and Singapore. B}^ B,. Shelford, M.A., 

 C.M.Z.S., Cm-ator of the Sarawak Museum. "With 

 Appendices containing Descriptions of new Species 

 by B. Shelford, Dr. Karl Jordan, C. J. GtAhan, the 

 Bev. H. S. GoRHAM, and Dr. A. Senna. 



[Received November 13, 1901.] 



(Plates XIX.-XXIII.^) 



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 abstiuct of 

 which, ai'ranged 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 dis- 

 cussed 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. 



^ For explaii«tion of tlie Plates, see page 331. 



