126 MR. A. G. BUTLER ON THE GENUS TERACOLUS. [Jan. 18, 



8. Revision of tlie Lepidopterous Geniis Teracolus, with 

 Descriptions of the new Species. By Arthur Gar- 

 diner Butler, F.L.S., F.Z.S. 



[Eeceired December 8, 1875.] 

 (Plates VI. & VII.) 



The Butterflies treated of in the present paper, although admitted 

 by all to be very pretty, are by no means favourite objects of study 

 with the lepidopterist. 



Whenever a genus is composed of striking and, at the same time, 

 sharply defined species, plenty of entomologists are always ready to 

 work at it ; but when, as in the present instance, there is some diffi- 

 culty in ascertaining the amount of variation obtaining in the dif- 

 ferent species, it will be found that lepidopterists are not unfrequently 

 content to catalogue all doubtful forms as varieties of known species, 

 often giving to the world a false view of their geographical distri- 

 bution, and thus hindering instead of advancing science. 



The genus Teracolus was first founded by Swainson, in his ' Zoolo- 

 gical Illustrations,' for the reception of his T. subfasciatus. But a 

 few years since I extended it for the reception of all the insects 

 formerly constituting the genera Idmais and Callosune, there being 

 no reason, but that afforded by colour, why they should ever have 

 been kept separate. 



Until quite recently I was unable, from lack of adequate material, 

 to attempt a revision of this very difficult group ; but the kindness 

 of Mr. E. C. Buxton, in presenting to the Museum his valuable col- 

 lection of African " Orange-tips," has at length put me into a fair 

 position to work out the whole of the African species. 



In order to make the present paper more complete, Mr. F. Moore 

 has very generously lent me the whole of his Indian specimens, thus 

 enabling me to avoid errors in determining the Asiatic species — our 

 deficiencies in Syrian forms being also partially met by the assistance 

 of my friend R. Meldola, who has put into my hands several species 

 collected by the late Mr, J. K. Lord. 



It would be easy to show that the present genus contains but few, 

 if any, very sharply defined species. It is not improbable that, when 

 we know the Butterflies of East Africa, Arabia, Syria, and Persia 

 more thoroughly, we shall be able to show an unbroken gradation 

 from one end of the group to the other. At present we get a nearly 

 perfect transitional series from T. subfasciatus to T. ione, thence 

 through T. halimede to T.fausta, calais, and allies, on the one hand, 

 and to T. eupompe and allies on the other ; from the latter we can 

 run on, almost without a break, through T. eucharis to T. inter- 

 ruptus, and thence to T. evippe. 



If the plan of " lumping " species were to be adopted in this genus, 

 every year would probably decrease instead of adding to their num- 



