16 



portion, counting from the costa, stand out further from the base 

 than the rest. The inner dark band is much widened out in the 

 centre, where it contains a spot of the colour (or of one of the 

 shades) of the lighter bands. This we will refer to as the " li<iht 

 spot." The basal light band consists of five spots, of which the 

 lowest, that on the inner margin, is frequently absent, the central 

 one being the smallest (usually much the smallest), the diminution 

 in size corresponding with the swelling in the centre of the inner 

 dark band, the light spot in which has a tendency in all the species 

 to break occasionally into the small central spot of the basal band. 

 The actual base of the wing is again behind this band, and is cut 

 up by the nervures into four spots, of which, as a rule, only the 

 third (which is roughly triangular, the base resting on the fourth 

 spot of the basal band) is at all conspicuous ; sometimes, however, 

 when the central spot of the basal band is unusually small, the 

 second spot is easily distinguishable ; the fourth, though much the 

 largest and frequently invading the whole area of the fifth spot of 

 the basal band, is inconspicuous, as it has the appearance, especially 

 when this fifth spot is absent, of beinj^ a continuation along the 

 inner margin of the inner dark band. The light bands will be 

 referred to as the " teruiinal," "central," and "basal," the dark 

 bands as the " outer" and "inner." In idiina the outer and central 

 bands are quite undivided, which is therefore probably the original 

 form, especially as the central is often undivided also in aateria ; a 

 regular division of the outer band is also confined to the athalia- 

 group, but it is interesting to trace the elements of the full pattern 

 in those species in which it only appears in part. To take the three 

 British species : the whole pattern occurs in athalia ; in aurinia the 

 tenninal, iuner, and basal bands are also as clearly defined, but there 

 are only slight indications at the costa of the division of the central 

 band, whilst the Innular formation of the outer portion of the outer 

 band is only indicated by the roundness of the paler spots, which in 

 this case contain black dots. These dots are of no phylogenetic 

 value, since not only are they present and absent in nearly related 

 species, but several species sometimes possess and sometimes lack 

 them. In ajnthia for example they may be present or absent, in 

 cinxia, which normally has them, they are occasionally absent, and 

 in plmbe, which is normally without them, they frequently appear. 

 In cinxia it is not easy to realise the lunular shape of the inner 

 portion of the terminal border owing to the fact that the nervures 

 are not black and that the division of the terminal band is only 

 indicated by dots, as is also the case with the outer band, but the 

 central band is divided, also b}^ dots, throughout its length, and the 

 inner, and often the basal, band is fully developed. It would be an 

 interesting study to follow this up through the foreign species as 

 well, but time will not permit, and I can only hope in this, as in 

 other matters I have touched upon, to throw out suggestions for 

 interesting and profitable study on the part of those who have more 

 leisure and more ingenuity than myself. 



