312 Dr. Frederick A. Dixey on the 
in a greater or less state of development in all the 
genera of the particular group of Pierines now under 
discussion. Other features, which appear first in Teracolus 
and will be met with again later on in the history of the 
er ae are the pinkish fringe of the wings in some species 
(as 7. wallengrenii, and often in T. protractus) and the 
faint pinkish Colias-like spot or patch at the root of the 
cell in the hindwing underside of others (as J. tri- 
punctatus, T. celestis 2, T. eupompe, and T. theogone). 
The genus Jaias follows easily upon Teracolus, the 
females of the two genera showing, as usual, a greater 
affinity in colouring than the males (compare, for instance, 
the males and females of 7. tone and J. marianne *). 
Series § is often well preserved in Jvias, especially on the 
underside and in the female; the discoidal spots are also 
prominent, and begin on the lower surface to assume an 
ocellate character. In neuration, Jxias differs only 
slightly from Teracolus; while the pupa, as shown in 
drawings by Captain Boys of I. marianne and I. evippe 
(Coll. Hope), has the same characters as Teracolus in a 
more strongly-marked condition. 
From the usual system of colours and markings in 
Ivias, there can be little doubt that that genus represents 
the transition from T'eracolus to Colias. The underside 
of several species of the latter genus (for instance, C. 
subaurata) is strongly recalled by that of I. marianne, 
in which the Colias-like condition of the discoidal spots 
is one of the most noticeable features. The affinity 
suggested by the colour-pattern is borne out by the 
structure of the antennz, which in Jvias show a distinct 
approximation to the gradually thickened form so 
characteristic of Colias and its immediate allies. The 
pupa in Colias, as in Teracolus, seems to vary somewhat 
in form; but in all known cases it shows a tendency, 
sometimes strongly pronounced, towards the acuminate 
and boat-shaped outline characteristic of this group of 
genera. 
cit., vol. iil., p. 82. I refrain from using the terms “ wing-covers” 
or « wing-cases,” the inapplicability of which has been shown by 
Prof. Poulton (Trans. Linn. Soc., 1890, series ii., vol. v., part 5, 
. 188). 
* Mr. Butler points out the intermediate character of the two 
African species, Jzias eulimene and I. venatus. Proc. Zool. Soc., 
1871, p. 254. 
