A Revision of the Genus Ixias. 133 



may be considered almost perennial in habit, whei'e its own 

 disabilities as a food-collector, on account of local inertia and 

 the total absence of tentacles, were supplemented by the life- 

 sustaining currents induced by its more active neighbours. 

 These conditions are near Philadelphia furnished by Urna- 

 tella gracilisj Leidy, and Pottsiella erecta, Kr^pelin (^Paludi- 

 cella erecta, Potts). I regret to be obliged to add that I am 

 not aware that either of these has been collected in any other 

 neighbourhood. 



Philadelphia, 

 August 19th, 1897. 



XXII. — A Revision of the Butterflies of the Genus Ixias. 

 By Arthue G. Butler, Ph.D., F.L.S., F.Z.S., &c. 



The present genus is confined to the Old World, being 

 found throughout India and Ceylon, Burmah, Siam, China, 

 and south-eastwards to the Celebes and Timor. 



Ixias in general aspect resembles certain groups of the 

 genus Teracolus, but is readily distinguishable by the neura- 

 tion, the first two branches of the subcostal vein in the 

 primaries being emitted wider apart, the upper radial emitted 

 from the subcostal vein well beyond the end of the cell 

 (expressed in the recently adopted phraseology this would 

 stand as "veins 6, 7, and 8 stalked"). In the secondaries 

 the discocellulars are much more oblique than in Teracolus. 



The seasonal variation of Ixias differs somewhat from that 

 of Teracolus, nor is it quite consistent in its character 

 throughout the genus. As a rule the wet form has heavy 

 borders to the wings on the upper surface and scarcely any 

 markings on the under surface (often only a black dot at the 

 end of the discoidal cells and a spot at the external angle of 

 the primaries), but in some of the species there appears to be 

 no wet phase of marking and coloration, and in others the 

 wet-season form shows dark spots on the under surface 

 occupying the exact positions of the ocelloid markings charac- 

 teristic of the dry season. 



Group 1. (Type /. venilia.) 



Apical two thirds of primaries above veined with black • 

 under surface always showing dry-season markings ; the 

 only probable seasonal difference consisting in the width of 

 the border of the secondaries on the upper surface; it is not. 



