400 MR. H. J. ELWES ON BUTTKRKLIES FROM SIKKIM. [May 2, 



nerve with square black spots, which, in fact, give the fringe the 

 appearance of being alternately black and white. 



These fourteen specimens agree perfectly in form and vary but little 

 in size. They are very similar in their pattern and tint, but the red 

 spots do not agree in any two specimens. Some have one on the 

 costa of fore wing, another just below it, and a third on the posterior 

 margin. In others one, two, or all of these are yellowish, plain black, 

 or nearly absent. On the hind wings there are usually three large 

 black spots with red centres ; but in two specimens the centre of the 

 spots is yellow, and in one the spots are plain black. 



Tliis species, which I propose to distinguish as var. si/ckimetisis, 

 occurs at great elevations on the frontier of Sikkiin and Tibet. I took 

 it myself on an unknown pass by which I crossed from the upper 

 Lachoong valley to the Cholamoo lake in Tibet, at an elevation of 

 nearly 19,000 feet, in September 18/0. I found a single pair in 

 copula, which I put in an envelope and gave to Mr. Atkinson on 

 my return to Darjeeling. These specimens are now in the Hewitsou 

 collection, under the name of P. simo, w hich at first sight they very 

 closely resemble. I believe, however, after careful examination of 

 my series, and of all the specimens of P. sinio which exist in England, 

 that the two species are well defined by structural characters, which 

 in this very difficult genus are of much more importance than size 

 or colour. 



Parnassius acco. 



P. acco, Gray, Cat. Lep. Brit. Mus. p. 7Q, t. xii. figs. 5, 6. 



P. simo, Gray, I. c. t. xii. figs. 3, 4. 



After a careful examination of the types of these species and of 

 three others in Messrs. Godman and Salvin's, and one in the Hewitson 

 collection, which are all that I know of in England, I have come to 

 the conclusion that they are but varieties of one species, differing 

 only in size and in the number and colour of the spots. They are, 

 however, distinguished from P. epaphus by the colour of the fringes, 

 which in fresh specimens are plain white, but in slightly worn ones, 

 such as the type, are dark, but still quite plain. Tlie antennae also 

 are plain black, not ringed as in P. epaphus and P. sihJcimensis, and the 

 ground-colour of the wings is distinctly greyer and less pure white 

 than in P. sihMinensis. The fore wings also seem constantly more 

 pointed at the apex, and more rounded at the posterior angle. These 

 characters are not to be shown plainly by a figure, but are evident 

 when a series of the insect is carefully examined. 



The female figured by Gray (fig. 6) is much more heavily spotted 

 on the bind wings than one in Mr. Godman's collection ; but the 

 species seems less variable in this respect than P. epaphus, none of 

 those I have seen of P. acco or P. simo having any red marks on the 

 fore wing. The underside is perhaps more difi^erent from P. sikA-i- 

 mensis than the upper, but the difference cannot be explained in 

 words. 



This species is known from four specimens in the British Museum 

 and one in the Hewitson collection, collected by Major Charlton in 



