400 MR. H.J. ELWES ON BUTTERFLIES 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. 
This species, which I propose to distinguish as var. stkhkimensis, 
occurs at great elevations on the frontier of Sikkim 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 1870. I found a single pair in 
copuld, which I put in an envelope and gave to Mr. Atkinson on 
my return to Darjeeling. These specimens are now in the Hewitson 
collection, under the name of P. stmo, which at first sight they very 
closely resemble. I believe, however, after careful examination of 
my series, and of all the specimens of P. simo 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. 76, t. xii. figs. 5, 6. 
P. simo, Gray, J. 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. The antennze also 
are plain black, not ringed asin P. epaphus and P. sikkimensis, and the 
ground-colour of the wings is distinctly greyer and less pure white 
than in P. sikkimensis. 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 hind 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 different from P, sikki- 
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 
