DISTINCTIONS OF SEX. 



541 



tinguishes the male, and the light-coloured marks upon the upper 

 wings are white. The lower pair of wings are also dull black, 

 relieved by large yellow marks, which are apt to fade into yel- 

 lowish grey. The al:)domen is yellow, but not nearly so bright 

 as in the male. Almost the only point of resemblance between 



Fig. 292.— Paijilio ijiouoiims. Male. Underside. 

 (Block, green, and crimson.) 



the two sexes is the crimson tuft on the shoulders, which is aa 

 brilliant in the female as in the male. 



Even from this single instance the reader will see that 

 there was much excuse for the mistakes which Linnaeus made 

 when arranging these insects. Two of them are rather remark- 

 able, on account of a phenomenon which sometimes occurs to 

 insects, and is well known to practical entomologists. It some- 

 times happens that one side of an insect is male and the other 

 side female. Thus Linnseus had described PapUio Polycaon as a 

 Greek and rapilio Laodocus as a Trojan. Yet a specimen was 

 found which had on the right tlie \siugs of I'olycciun and on 

 the left that of Laodocus, thus proving that they were both the 



