566 MR. H. W. BATES ON THE AMAZON-VALLEY HELICONIDE LEPIDOPTERA. 



tion whose adaptation is complete. As to the fore wings, the vacillating nature of the colours 

 is seen in figs. 4, 6, and 8 of Plate LV. in the clearest manner. The hind wings appear very 

 peculiar, on account of the milky colour ; but this is shown to arise by variation in TihomuB, which 

 exhibit all the grades of variation from dusky to white nervures and ground of the hind wing. 



Fig. .5. Leptalis Nehemia (of authors). — New Granada and S. Brazil. 



Figured to show the normal form of the family (PieridcB, called in England " Garden White" 

 Butterflies) to which Leptalis belongs. The contrast in form and colours points to the conclu- 

 sion that all the other forms of Leptalis are perverted from the usual facies of the family by long- 

 continued process of adaptation to the Heliconidse, in whose company (each species with its 

 Heliconian model) they are solely found. 



Fig. 6. Leptalis Theono'e, var. Argochlo'e. — St. Paulo. 



Fig. 6 c. Ithomia Virginia (Hewits.). — St. Paulo. 



The links of modification may be traced also with respect to this apparently distinct Leptalis. 

 The shape of the spot of the fore wing is seen to be very variable in figs. 1, 2, 3 of this Plate, 

 and in 9 and 4 of Plate LV. 



Fig. 7- Leptalis Amphione, var. Egaena. — Ega. 



Fig. 7 a. Mechanitis Polymnia, var. Egaensis. — Ega. 



Fig. 8. Leptalis Orise (Boisduval). — Cupari, 55° W. long.; also Cayenne. 



Fig. 8a. Methona Psidii (Linnaeus). — Cupari; also Cayenne. 



ERRATUM. 



At p. 515, after the characters of Family 2. Papilionid^, insert 

 Subfam. 1. Papilionin^e. 

 Subfam. 2. Pierin^. 



