INTRODUCTION. 13 



.affinities of the species. While great dissimilarity in coloration 

 of different individuals is consistent with their specific identity, 

 in a wider sense the colour may be found to have a very great 

 degree of constancy and to form the most distinctive and 

 important feature of large groups of species. Various natural 

 groups will be indicated in this volume which, varying greatly 

 in structural features, are recognisable by a definite system of 

 coloration common to all their members. 



The colouring of the lower surface is of greater significance 

 from this standpoint than that of the upper surface, being much 

 more free from individual variation. The colouring of the upper 

 surface varies to such an extent in many species that some speci- 

 mens appear light with dark markings and others dark with light 

 markings, but in practically every case a glance at the lower 

 surface is enough for the relegation of an insect to its proper 

 category light or dark. For instance, Anomala varicolor and 

 A. ruficapilla are normally light-coloured species with some dark 

 dorsal areas, but specimens of both occur in which the dark colour 

 predominates, while in another variable species, Anomala, rugosa, 

 the female is predominantly light above and the male predomi- 

 nantly dark ; but in all these the lower surface, in the dark and 

 light specimens alike, will be found to be pale-coloured. Anomala 

 transversa again may be entirely black, black with a pale trans- 

 verse band upon the elytra, or almost wholly pale above ; but 

 here also the lower surface, which is invariably black, reveals at 

 once that the dark phase is the original and the light the acquired 

 condition. 



In this great genus Anomala, which is so huge and various as 

 to afford abundant materials in itself alone for the study of very 

 many entomological problems, certain groups have been separated 

 as distinct genera on account of the shape of the mesosternum, 

 which differs to a very striking extent, but which seems to have 

 in reality much less importance than has been generally attached 

 to it. There is a group of closely related Malayan species, 

 typified by Anomala citrina, Lansb., all of them having the same 

 peculiar pale greenish-lemon tint, but all differing in the degree 

 of development of the mesosternum, which may have a strong 

 pointed process or none at all, showing that as a group-character 

 this structural feature is of less importance than the colour. 



The most cursory survey of the genus will reveal amongst its 

 very heterogeneous elements two conspicuous types (1) long and 

 rather parallel-sided species of pale colour, and (2) short-bodied, 

 oval species, generally of some shade of rich green. After long- 

 continued efforts to define these groups by means of structural 

 characters, I found myself obliged to reject all the latter as 

 insufficiently stable and to recognise that the type of coloration 

 really forms the most deep-seated and natural distinctive feature. 

 The presence or absence of any degree of metallic lustre is a very 

 important indication of the affinities of a species. Anomala mar- 

 gimpennis is a pale, elongate insect, which seems at first sight to 



