804 Professor E. B. Poulton on Mimetic Forms of 



spiciions in latifascinta, and this is well niatclied excejat 

 in form by the mimic. In fresh specimens moreover the 

 ground colour of both wings in the Tore model and mimic 

 is of a distinctly brownish shade of black, wanting in the 

 dark ground of the more eastern pair. The discal baud 

 of the hind-wing in P. latifasciata (Plate XXII, Fig. 8) 

 is fulvous and broader than the white band of qvadri- 

 eolor (Plate XXI, Fig. 3) : the triangular basal brown 

 patch of the hind-wing under-side is reproduced above 

 in both species of Plancma, but the black spots are indis- 

 tinctly seen on tlie upper- side of latifasciata, while the 

 chief members of the group are conspicuous, being in fact 

 reproduced on the upper-side of qKadricolor. In toruna 

 the discal patch on the hind-wing is fulvous, and the effect 

 at a little distance is singularly like that of the model. 

 It is however produced in a different way ; for the uniform 

 bright fulvous tint of latifasciata is imitated by a fusion 

 of two distinct colour elements in tormina, — viz. the paler 

 fulvous ground colour of the patch and the deep fulvous 

 internervular and intracellular rays which traverse it. 

 The shape of the discal patch has also been modified into 

 close resemblance to the band of latifasciata, although a 

 trace of the angle, so well known and conspicuous in the 

 forms of johnstoni, remains as a guide, indicating the path 

 of evolution. The basal invasion by deep rich brown of 

 the pale jjatch on the hind-wing suggests the basal 

 triangular area of the Plancma model. On the under-side 

 the patterns of both model and mimic are reproduced in 

 paler shades, still maintaining their close resemblance. 

 The discal band of the hind-wing of Planema and the 

 corresponding patch of the Acriva are white, and in the 

 latter the cliaracteristic squarish shape is far more 

 prominent than on the upper-side. The basal spots of 

 the hind-wing under-side Avhich are so concentrated 

 towards the base in other forms of johnstoni are here 

 moved outwards and are placed upon and along the 

 borders of a rich brown triangular area resembling but 

 much smaller than that of the model. The foriina form 

 of johnstoni is one of the most interesting of the mimetic 

 appearances developed by this remarkable and protean 

 species. 



(4) Act xa johnstoni, form fckcscens, Oberthiir (I. c, PI. II, 

 f. 21). This, the last of a wonderful series, is one of the 

 most remarkable, the black ground colour persisting only as 



