70 Dr. A. G. Butler on the Old- World 



Terias excavata, Moore, P. Z. S. 1882, p. 252. 



Terias irregularis, Moore, t. c. pi. xii. fig. 3. 



Terias apicalis, Moore, t. c. p. 253, pi. xii. fig. 2. 



Terias asj^hodelus, Butler, P. Z. S. 1883, p. 151, pi. xxiv. fig. 13. 



Terias narcissus, Butler, I. c. •• oi« 



Terias Swinhoei, Butler, Ann. & Mag. Nat. Hist. ser. 5, vol. xvu. p. 21b 



(1886). 

 Tej-ias sijnplex, Butler, t. c. p. 217, pi. v. fig. 2, 



Terias coiitubernalis, Moore, Journ. Lina. Soc, Zool. xxi. p. 46 (188b). 

 Terias patruelis, Moore, t. c. pi. iv. fig. 5. 

 Terias fraterna, Moore, t. e. pi. iv. fig. 6. 

 Terias Andersonii, Moore, t. c. p. 47, pi. iv. fig. 8. 



India and Oejlon, Burma, and southward to Malacca, 

 including the Mero^ui Archipelago. 



This species well bears out Darwin's statement that common 

 and widely distributed species vary most. T. suava (com- 

 monly confounded with the broader-winged and far less 

 variable T. hecahe of S. China) exhibits more inconstancy 

 than any other species of Terias^ and consequently has 

 received numerous distinctive names. As every gradation of 

 upper-surface pattern, from the typical broad-bordered T. suava 

 to the narrow-bordered T. narcissus, is represented at all 

 seasons, it would seem to a superficial observer that many 

 species were represented by the forms of this butterfly ; when, 

 however, it is found that these forms are not limited to locality 

 and comprise a perfect transitional series, it becomes evident 

 that they represent one extremely variable species. 



In order to facilitate their identification I shall consider 

 these intergrades as separate varieties, beginning with the 

 most broadly bordered typical form and ending with those in 

 which the border is reduced to its narrowest limit. 



Var. 1. 

 T. suava = hecaheoides is the wet-season form, the inter- 

 mediate form is unnamed ; T. simuJata is the dry-season form, 

 from which T. contubernah's is practically inseparable. 



Var. 2. 

 T. merguiana is the wet-season form, the intermediate form 

 is unnamed ; T. excavata is the dry-season form, from which 

 T. Andersonii is inseparable. 



Var. 3. 

 The wet and intermediate forms are both unnamed ; T. fra- 

 terna is the dry form. 



Var. 4. 

 The wet and intermediate forms are both unnamed ; 

 T. purreea=: patruelis is the dry form. 



