Mr. R. I. Pocock on Isometrus amevicanus [Linn.). 53 



VII. — On a new Chalcosiid Moth obtained in Formosa by 

 Mr. H. E. Hohson. By Arthur G. Butler, F.L.S. &c. 



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. 



Chalcosiidse. 



Erasmia Hobsoni, sp. n. 



? . Allied to E. 2^ulcliella 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- 

 disii' 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 E. pulchellaj 

 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 E. jmlchella. On the under surface tlie 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. Expanse of wings 73 

 millini. 



N. Formosa {Hobson). 



The female oi E. jiulchella expands about 90 millini. 



VIII. — On Isometrus americanus [Linn.), xoltli a Descrip- 

 tion of a new /Species of the Genus. By \i. I. PocoCK, of 

 the British (Natural-History) Museum. 



Isometrus americanus (Linn). 



This species was described by Linnreus (Mus. Adolph. 

 Frid. p. 84, 1754) ; subsequently (in Syst. Nat. ed. 10, p. (j25, 

 1758) its name was altered to europojus, and as europieus it 



