1886.] MR. H. J. ELWES ON THK GENTJS PARNASSIUS. 35 



P. Acco, Gray. 



Parnassius acco, Gray, Cat. Lep. Brit. Mus. i. p. 76, t. 12. 



figs. 5, 6 (1852). 



P. acco, Elwes, P. Z. S. 18S2, p. 400. 



Of this rare and very curious species we know hardly anything. It 

 seems to be confined to the elevated desert regions of Ladak, and 

 not more than six or seven specimens are known to exist in collec- 

 tions, viz. two in the British Museum (the types), two in Messrs. 

 Godman and Salvin's collection, one in my own, which I owe to 

 their kindness, and one, which I have also examined, in Baron 

 Felder's. The two first of these were collected along with the types 

 of P. charltonius and P. simo in Ladak many years ago by Major 

 Charlton, at about 16,000 feet. The next three were taken by the 

 late Mr. Shaw on his journey to Yarkand, at Lapsang, soutli of the 

 Karakoram pass, about 1 7,000 feet above the sea, and were given by 

 him to Mr. Bates, whose collection of Lepidoptera passed into 

 Messrs. Godman and Salvin's hands. The last was taken by the 

 late Dr. Stoliczka on the Samanda pass, 17,000 feet, near Lake 

 Tsomoriri in Ladak. 



I have also a single small specimen, which came, along with 

 P. sikkimensis, from the Tibetan frontier, north of Sikkim, and which 

 I cannot separate from P. acco, though in size and colour it is more 

 like P. simo, and led me at first to consider those two species as one 

 when I first received it. 



They all agree very well in the important characters, having black 

 antennae and whitish fringes ; but the most remarkable character is 

 the pouch, which in this species develops a keel of such extra- 

 ordinary depth, that when sitting on level ground the abdomen of 

 the insect must be elevated at a considerable angle. This remark- 

 able pouch is similar in two perfect specimens, the one figured 

 (Plate II. fig. 3) being from Mr. Godmau's collection. 



A more minute examination of them shows that the fringes of the 

 wings of P. simo are very difi"erent, and though neither the British 

 Museum nor Hewitson's specimen has the pouch in a perfect 

 condition, yet I have little doubt that the pouch of P. simo will 

 be also found to be difi'erent from that of P. acco. 



Since 1881 I have had several collections from the same part of 

 Tibet, and obtained a few more specimens of P. sikkimensis, but this 

 single one of P. acco remains unique from that region, and none of 

 the numerous collections made at DarjiUng, which sometimes contain 

 specimens from high elevations, have, as far as I know, ever included 

 any Parnassius except P. hardwickei. 



P. SIMO. 



Parnassius simo. Gray, Cat. Lep. Brit. Mus. p. 76, t. 12. figs. 3, 4. 



Of this species almost nothing is known; there exist in all museums, 

 to my knowleuge, but four specimens — two in the British Museum, 

 collected by Major Charlton in Ladak, and two others, of which one 

 is in the Hewitson and one in M. Oiaerthiir's collection, and both 



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