ON PARNASSIUS PH(EBUS. 341 



Central and Eastern Asia. It has seemed to me a doiilDtfiil case 

 as to the two insects being one species. I have had a good 

 number of P. smintheus collected for me in the Rockies of Colo- 

 rado, Nevada, and Utah, and on comparison with P. delius (Esp.) 

 — Iiihoehus (Fab.) they show constant differences as follows : — 



1. Phoehus has a more rounded contour of primaries in both 

 sexes, the costa of primaries of smintheus being straight for two- 

 thirds its length, unlike pha'hiis, which is slightly arched from 

 base to tip ; apex of primaries of smintheus much more pointed, 

 to a greater degree in male than in female examples. 



2. Palpi and head of smintheus clothed with pale golden 

 hairs ; pltoebus with fewer, longer, and coarser dark grey ones. 



3. Wings of jj/i«?6us more diaphanous; more pronounced at 

 the outer margins. 



4. Fringes at the terminations of the nervures, and all 

 black markings, on smintlieus more emphasized, and particularly 

 a row of semilunar dark spots forming a decided band outside 

 the cell on primaries, and in a less degree on secondaries, of both 

 sexes of smintlieus ; those on secondaries very much pronounced 

 in the female, less in the male, and in female and male pha'hus 

 almost absent. Ground colour of all wings of smintheus paler. 

 The black patch of anal margin of secondaries running round 

 the anal and lower edge of discoidal cell, most noticeable in 

 females. I have two females where it spreads over a very 

 considerable portion of cell, almost meeting a part of this band, 

 which runs out along the upper and costal edge of the cell. 



5. Antennae of pho'hus gradually swelling from half its 

 length to the club. Shaft slightly stouter. Antennae of smintheus 

 abruptly clubbed, the club thicker at its greatest diameter than 

 phoehus ; club occupying only one-third or less of the antenna. 

 Shaft more slender than phoehus. 



6. Body and anal margins of secondaries of phoehus more 

 strongly clothed with hair than smintheus. 



When I have a greater number of pouched females oi pho'hus, 

 I shall carefully examine them ; I have but two by me, and these 

 show a slight difference between themselves ; but one slight 

 character they have in common, which I fail to notice in seven 

 pouched females of smintlieus. The anterior end of the keel 

 seems to end in a ram (if one may still keep to nautical terms) ; 

 I do not, however, place much faith in this, as both specimens 

 may have been taken in coitu before the complete development 

 of their pouches, and the anterior projection may be the point 

 of the keel at which the additions of the pouch-forming fluid 

 were communicated to the growing keel. However, I think 

 enough has been written to show the distinctions of the two 

 forms, especially when one considers the isolated habitat of 

 smintheus along with the other characters. That they are closely 

 allied I do not doubt; that they are both one species I cannot 

 admit. 



