284 Professor I. B. Poulton on Mimetic Forms of 
cover, at some point in the wide territories between 
Abyssinia and Zanzibar, females of the J/erope-group 
exhibiting stages intermediate between the long-tailed 
mimetic females of P. antinorii and the entirely tail-less 
ones of P. cenea.” 
It was reasonable not to attempt to name this primitive 
variety while it remained as a single example; but now 
that it has been discovered in large numbers as one of the 
female forms of the sub-species polytrophus, Jordan, on the 
Kikuyu Escarpment, the case is different. It is one of the 
most instructive if not actually the most instructive of all 
the female forms of dardanus; and I propose to call it 
triment, in honour of the great naturalist who solved the 
mystery, and laid a firm foundation for all future work 
upon the most interesting and complex example of 
mimicry as yet known throughout the world.* 
The specimen referred to by Mr. Trimen is here repre- 
sented ona slightly reduced scale on Plate XIX, Fig. 1. In 
Plate XVIII, Fig. 1, one of the smaller ¢vimenz forms from 
the Kikuyu Escarpment is represented of about the 
natural size. Of these there are four in the Hope Depart- 
ment. Judging from these four specimens the ground 
colour is sometimes yellow, exactly like that of the male 
(1), sometimes of a rather paler shade (2), and sometimes a 
little darker (1). 
(a) Occasional occurrence of rudimentary “tails” to the 
hind-wing of trimeni and hippocoon. 
The triment form frequently possesses ancestral 
characters additional to those described in the Presiden- 
tial Address. The most interesting of these supplies the 
confirmation of Mr. Trimen’s prediction that stages would 
be found “intermediate between the long-tailed mimetic 
females of P. antinorw and the entirely tail-less ones of P. 
cenea.” ‘The specimen represented on Plate XVIII, Fig. 1, 
is seen to have a small but distinct rudimentary “ tail,” 
containing an extension of the third median nervule. 
This nervule also enters the tail in the male, showing that 
the rudimentary tail of the female is entirely homologous 
with that of the other sex. The other three specimens of 
polytrophus 2 f. trument do not exhibit this feature, but it is 
* It is perhaps unnecessary to say that I allude to the great mono- 
graph in Trans. Linn. Soc., vol. xxvi, 1870, Pt. ILI, 1869, p. 497. 
