— и — 



hengaliarius Guénée, from Sikhim, Khâsis, Schillong, amXBiston 

 Mbvtarius Obertliiir from Tliibet (Biet), Kliam Mountains (Po- 

 tanin), and Central and AVestern China (Leech). 



It differs from typical hengaliarius^) in ha\ing 1) ground- 

 со1ош' рш'е white, 2) antennae of male pectinated not tili the 

 end, 3) Ist and 2nd somites of abdomen blackish-brown, 4) post- 

 medial black line of fore wing between veins 1 and 2 highly 

 excurved outwards, 5) oiiter margin of bind wing deeply excised 

 between veins 4 and 6, 6) medial space of fore wing without two 

 yellowish bands, 7) a brown triangulär spot on apical part of 

 Costa beyond the postmedial line, 8) black lines of both wings not 

 so regularly ciu'ved, but crenulated, 9) no lunulate black spots 

 between veins 4 and 6 in submarginal area of fore wing; etc. 



From Biston tJiibetariits Oberth.^) my species diifers in hav- 

 ing 1) Ist and 2nd somites of abdomen black, the rest not ringed, 

 2) wings narrower, 3) black lines much finer and not so rectili- 

 near, 4) broad medial line absent, 5) flexure of postmedial line of 

 fore wing not attaining on median vein the end of cell, so that 

 the medial area is much broader, 6) band inside antemedial line 

 brown, not yellow, 7) black spot in the middle of inner margin of 

 liind wing absent, 8) outer margin of bind wing deeply excised 

 between veins 4 and 6; etc. 



Lastly from Biston regalis Moore (from Japan, N. W. Hima- 

 layas, Khasis, Central China) it differs by the white colour of 

 head, thorax and wings; the antennae being pectinated not to 

 near apex; the margin of bind wing being excised. But the form 

 of transversal lines of both wings is more similar to Biston rega- 

 lis^ than to any other species ^). 



2) I had for examinatiôn a male spécimen of В. hengaliarius Guén. from 

 Imlia, and a maie spécimen of B. thibetariics Ob er th. from Kham Mountains, both 

 preserved now in the collection of H. I. H. the Grand Duke Nicholas Mi- 

 khaïlovitch. 



3) Hampson writes: «postmedial sinuous line of bind wing (of B. regalis) 

 angled outwards at vein 4», but in the figure (Butler, 111. of typ. specim. of 

 Lepid. Heter. of Brit. Mus. Part VII, pi. 136, fig. 1) this line is excurved at vein 5. 



