INVESTIGATIONS REQUIRED 171 



The proportion of such dark forms in various 

 parts of the immense range of archippus would 

 be another interesting inquiry. 



THE MODIFICATION OF THE LIMENITIS MIMIC 

 OF DANAIDA PLEXIPPUS INTO A MIMIC OF 

 THE STEIGOSA FORM OF D. BERENICE IN 

 ARIZONA 



The differences between L. archippus and the 

 form hulsti (Edw.) are more striking than those 

 wliich distinguish floridensis from the former. 

 The upper surface of the hind wing of hulsti 

 retains or more probably has recalled distinct 

 traces of the white band, although the black 

 stripe is evanescent. It is probable that, upon 

 the wing, these vestigial white markings produce 

 a general likeness to the pale-streaked hind-wing 

 upper surface of strigosa. Other points in which 

 hulsti differs from archippus and approaches stri- 

 gosa are the reduction of black and the general 

 appearance of the white spots in the subapical 

 region of the fore wing, and the dull tint of the 

 ground-colour. I have had hardly any experi- 

 ence of this interesting form and owe the above 

 details to Dr. W. J. Holland's figure and descrip- 

 tion.^ It is obvious that all the investigations 

 suggested in the case of floridensis are, mutatis 

 mutandis, equally available and equally important 

 in the form hulsti. 



' Butterfly Book, 84, 185, PI. vii. f. 5. Dr. Holland fully recog- 

 nizes the mimetic significance of the pattern and colouring of 

 hulsti. 



