Mr. R. I. Pocock on Isometrus americanus (Zinn.). 53 
VII.—On a new Chalcostid Moth obtained in Formosa by 
Mr, H,. E. Hobson. By Artuur G. Butter, F.L.S. &e. 
THE following new species was in a series of moths sent to 
us by Mr. Hobson about six years ago, and of which I have 
on several occasions commenced drawing up a list, but have 
been prevented from doing so by more pressing work. 
Chalcosiida. 
Erasmia Hobsoni, sp. n. 
9. Allied to £. pulchella of India, but smaller and less 
brilliantly coloured ; the basal metallic green markings on 
the primaries noticeably smaller ; the irregular oblique band 
beyond them broader and of a deep ochreous (instead of red- 
dish clay-colour) ; the central metallic green markings nar- 
rower, the broad macular white belt less broken up, slightly 
broader, and with scarcely perceptible greenish edging; all 
the green streaks on the apical area and external border 
replaced by grey: secondaries whiter than in H. pulchella, 
with the metallic bluish-green colour confined to the basal 
sixth, not extending forwards into the cell, the black external 
border only narrowly edged internally with green, which 
colour does not extend along the veins or across the border, 
as in &. pulchella. On the under surface the differences are 
similar, the reddish clay-coloured markings being replaced by 
clear ochreous, and the green stripes on the external areas of 
the wings almost wholly obliterated. Hxpanse of wings 73 
millim. 
N. Formosa (Hobson). 
The female ot #. pulchella expands about 90 millim. 
VIII.—On Isometrus americanus (Linn.), with a Descrip- 
tion of a new Species of the Genus. By R. I. Pocock, of 
the British (Natural-History) Museum. 
Tsometrus americanus (Linn). 
This species was described by Linneus (Mus. Adolph. 
Frid. p. 84, 1754); subsequently (in Syst. Nat. ed. 10, p. 625, 
1758) its name was altered to ewropwus, and as ewropeus it 
