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VII. On Sexual Dimorphism in Beetles of the family 

 Rutelidse. By Gilbert J. Arrow, F.E.S, 



[Read March 1st, 1899.] 



The recorded examples of Sexual Dimorphism among 

 Coleoptera, other than those which consist in simple 

 differences of development of various parts, such as the 

 legs, antennte, or mandibles, are at present very few. 

 This is no doubt partly owing to the sexes having been 

 regarded as distinct species through the attention of 

 Coleopterists not having been sufficiently directed to the 

 matter, and it is therefore well that observations, however 

 incomplete, upon the occurrence of this interesting phe- 

 nomenon in any group should be recorded in order to 

 direct the attention of other workers to it, and thus at 

 least diminish the serious complication of nomenclature 

 which results from its neglect. This is of special import- 

 ance in a great and heterogeneous assemblage such as the 

 genus Anomala, whose swollen ranks already include 

 considerably more than 500 described species of many 

 different types, the merging of which into a single genus 

 has proved extremely inconvenient to systematists. 



A subdivision of the genus largely based upon the 

 structure of the claws is at present in use, but facts which 

 will be pointed out in this paper render this classification 

 inadequate and even misleading. It has long been recog- 

 nised that the degree of development of the claws of the 

 anterior legs usually distinguishes the sexes in this group, 

 and careful attention to this point will greatly increase 

 the value of systematic work ; but the occurrence of an 

 entire difference of claw-structure between the sexes has 

 only very recently been discovered. Sexual differences in 

 coloration in species of Anomala have also been pointed 

 out by Burmeister and Fairmaire, and the object of the 

 present paper is to bring together the recorded instances 

 of sexual dimorphism in the genus and to supplement 

 them by others which have been revealed in the course 

 of a revision of the specimens of Anomalct in the British 

 Museum collection. 



TRANS. ENT. SOC. LOND. 1899. — PART II. TjUNE) 



