( 540 ) 



Papilio xutkus and the Pacific Palaearctic P. mackaon hippoo-ates are 

 seasonally dimorphic. In the American species dimorphism appears to be purely 

 individual, the two varieties being produced by one female independent of the 

 season, as is the case in some African Precis. However, besides the dimorphic 

 P. bairdi from Colorado, no other dimorphic form has been actually reared. 

 Breeding from the eggs of one female of P. nitra, of an Oregon female of 

 P. bairdi f. oregonia, of a Mexican female of P. pnli/xenes asterius, and of a 

 female of P. polyxeiies americus, is a great desideratum. 

 Key to the American species : 



a. Yellow patch IP — SM- of forewing close to cell . . b. 

 Yellow patch M^ — SM- of forewing widely separated from 



cell, sometimes absent . ...... d. 



b. Abdominal sternites yellow, with two black lines . . c. 

 Abdominal sternites black, with or without indication of 



yellow lines Species No. 63. 



c. Anal ocellus with pupil ....... Species No. 61. c'. 



Anal ocellus without pupil Species No. 65. a- 



d. Palpus and breast entirely black ..... Species No. 64. 

 Palpus yellow ......... e. 



e. Abdomen dotted with yellow f. 



Abdomen with broad yellow lateral stripe . . . Species No. 61. i'. 



f. Discal spots of hindwing below reddish orange, more or 



less edged with yellowish cream ; or the yellow band 

 gradually shading off proximally, often extending to 

 base ; or the discal spots of upperside small, shaded 

 over with black, the baud being distal of cell on 



hindwing Species No. 60. 



Orange colour of discal band of underside of hindwing more 

 gradually shading off, the band always crossing apex of 

 cell, never extended to base . . Species No. 61. a and No. 62. 



60. Papilio polyxenes Fabr. (1775). 



Papilic Equea Achivus ajax Linnu, Si/st. Nat. ed. x. p. 462. n. 2G (1758) (imrtini) ; Clerck, Icon. his. 



ii. t. 33. fig. 3. J (1704). 

 Papilio Eques Trnjanus pobjxenes Fabricius, Syst, Ent. p. 444. n. 10 (1775). 



Linn^'s description of ajax applies, we think, to the present insect. The two 

 references given after the description count for nothing, a])plying to totally different 

 insects, the second being quoted later by Linnd himself under P. protcsilaus. In 

 the twelfth edition of Si/st. Nat. Linnd described P. xuthus as being very similar 

 to P. ajax. Esper (179{S) tried to explain this comparison by assuming that Linne' 

 meant Clerck's ajax, not his own. The three facts: (1) that Linne characterised 

 the anal ocellus of ajax and machaon by the same words {angulo ani falvo), (2) that 

 Clerck's work was executed under Linne's eyes — one might almost say under his 

 supervision, and (3) that in 1767 Liun6 describes P. xuthus as being very similar 

 to ajax, leave little doubt that the true ajax of Linn^ was the insect which Cramer 

 named asterius (corrupted by Fabricius into asterias), which is the same species 

 as polyxenes Fabr., but a different geographical race. However, since Linne 

 himself misled later authors by the erroneous quotation of Kaj. iii. ~ and Edw. 



