260 Mr. G. J. Arrow on Sexual Dimoiyliism in 



thicken to the extremity, where they are very wide and 

 furnished Avith two strong spurs, the upper one very 

 long. 



The very distinctive structure of the legs of this inject 

 will probably be found to require the ultimate forma ion 

 of a new genus for it, but in tlie present comprehen ive 

 state of the genus Anomala this does not appear advisc ble. 



Several cases of difference in coloration between ihe 

 sexes in species of Anomala Avere mentioned by Burmei. tor, 

 and M. Fairmaire has recently called attention to two 

 other instances ; and although one or two of these cases 

 must be regarded as doubtful, it will probably be fc md 

 that this form of sexual dimorphism is by no means rare 

 in the genus. 



The species contained in Burmeister's Handbucit of 

 which the sexes are stated to show differences of colora- 

 tion are the two common species A. lucicola, Fabr,, and 

 A. vidua, Newm,, from North and Central America re- 

 spectively, the S. European A. aurata, Fabr., A. trivittata, 

 Perty, and A. irrorcUa, Cast., from Java. Of these, how- 

 ever, the last must be excepted, as M. Lansberge has 

 pointed out that the form regarded by Burmeister as the 

 male is another species, to which he has given the name of 

 A.^ Inirmeisteri. 



The same author's statement that the colour differences 

 of A. vidua are sexual has been controverted by Mr. H. 

 W. Bates, who has stated that two of the three varieties 

 of the species are represented by both sexes in the Central 

 American collection of Messrs. Godman and Salvin. I 

 have carefully examined the specimens in this collection 

 now in the British Museum, and find that every individual 

 of the light form is a female, and those of the dark forms 

 males, with a single exception. The exceptional case of 

 the second form was probably in Mr. Bates' own collection, 

 or he may possibly have been mistaken, upon a cursory 

 examination, as to the sex ; but notwithstanding its 

 liability to exception, there is amply sufficient evidence 

 that Burmeister was justified in pronouncing this a case 

 of sexual dimorphism. Of nearly 70 specimens of the 

 species which I have minutely examined, the single 

 female mentioned above is the only exception to the rule 

 that the form with pale elytra is the female and those 

 with black elytra are males. 



