1909] Mimicry in the Butterflies of North America 219 



the white spots in the subapical region of the fore wing, and the 

 dull tint of the ground-colour. I have had hardly any exper- 

 ience of this interesting form and owe the above details to Dr. 

 W. J. Holland's figure and description.^" It is obvious that all 

 the investigations suggested in the case oi floridensis are, mutatis 

 mutandis, equally available and equally important in the form 

 hidsti. 



The geographical distribution of hulsti strongly supports the 

 conclusion that it was derived from archippus and not imme- 

 diately from an arthemis-like ancestor. I have not yet had the 

 opportunity of ascertaining whether this hypothesis is supported 

 by evidence derived from a careful study of the pattern. 



It is deeply interesting to observe that the same Limenitis 

 arthemis-like species, from which .archippus, floridensis, and 

 hulsti — mimics respectively of the three Danaidas, plexippiis, 

 berenice and strigosa — have been directly or indirectly evolved, 

 has also given rise to L. astyanax {ursula), the mimic of a Papil- 

 ionine model. Evidence in favour of the comparatively recent 

 origin of these mimicking forms is to be found in the well-sup- 

 ported facts which indicate that astyanax still interbreeds with 

 arthemis along their geographical overlap, and that it may even 

 occasionally pair with the sister species archippus.~° 



The earlier stages of archippus and astyanax are, according to 

 Scudder (1. c. 254, 255), with difficulty distinguished from those 

 of arthemis, but astyanax presents the closer likeness of the two; 

 a fact which, together with those referred to in the last para- 

 graph, points to the conclusion that it arose even more recently 

 than archippi^is, 



The further consideration of astyanax is best deferred until 

 some account has been given of the Papilionine models, and until 

 certain general conclusions have been discussed in the following 

 section. 



Bearing upon Theories of Mimicry of the Transfor- 

 mation Wrought by the Invading Danaidas. 



It has been shown that the Danaine models invaded America 

 from the Old World tropics, probably following a northward route. 

 Their patterns are but little changed in the new surroundings, 

 and they still keep the characteristic appearance of Old World 



''■» BuUcrfy Book, 84, 185, PI. vii. f. .5. Dr. Holland fully recognizes the 

 mimetic significance of the pattern and colouring of hulsti. 



-" Scudder, 1. c. 283, 289. Trans. Ent. Soc. Lond. (1908), 4?3, 474. 



