— 46 — 



by dark spots on tlie veins (in the other). Submarginal area of fore 

 wing brownisli-gray ; wavecl line and a stripe just beyond the 

 postmedial line very distinct, white. Outer margin spotted with 

 gray between the veins. Cilia very short, whitish-gray. 



Hind wing with the antemedial (subbasal) line absent; medial 

 line indistinct; discocellular spot clearly seen; postmedial line fine, 

 angled at vein 5; submarginal area brownish with very distinct 

 white waved line, and a broad white space between it and post- 

 medial line. Outer margin spotted indistinctly. 



Underside of all wings pure satin-white, Avithout markiugs, 

 except the gray discocellular spot, traces of medial line, and of 

 marginal spots. 



The species is closely allied to Biston betularius Linné, but 

 differs from the typical European form at first sight by absence 

 of the black points and streaks on wings, body, antennae; by 

 almost complète absence of markings on the underside, and by 

 the ground-colour being grayish-\vhite. Biston huebera/rius Bâil- 

 lon belongs evldently also to tliis group. 



I have had for description two fresh male spécimens, taken 

 by Mr. Bykow in the year 1893 at tlie village Kasakévitcheva 

 on the river Ussuii near the city of Khabarovsk (Amoorland). 

 Female unknown *). The spécimens are now preserved in the col- 

 lection of the Russian Entomological Society in St. Petersburg. 



I believe it may be mentioned here, that Staudinger gives 

 for the fauna of Amoorland the Biston betularius Linné tj'pe, 

 and its var. cognatarius Gué née; but ту spécimens of tliis spe- 

 cies from Kasakévitcheva differ very much from Guénée's 

 description (in having black spots beyond the collar, and on the 



4) Staudinger writes in his work Die Geometriden des Amurgebiets 

 (Deutsch. Ent. Zeitsch. Iris, X, 1897, p. 45): «das eine Ç (of Amph. betularius L.), 

 wohl eine Aberration, ist weisslich ohne alle schwärzliche Bestreuung, nur mit 

 den dunklen Querzeichnungen versehen». — It is not improbable that it was a fe- 

 male of my hypoleucos. 



