278 Dr. Frederick A. Dixey on the 
general correspondence in pattern with the old-world 
genera last named, which has been already referred to, 
involves a similar condition of the present series D. In 
none of them does any member of D assume the condition 
of a definite circumscribed spot; but in nearly all, the 
series exists as a portion of the original dark ground 
colour between the touches of intrusive white or yellow. 
In C. toca, D on the underside of the hindwing consists 
of an irregular dark ring with a yellow centre traversed 
by the disco-cellular nervules, this representing an early 
condition of the homologous ocellus in Oolias. 
Summary.—This series also, like those already treated 
of, represents a local survival of the original dark ground- 
colour. Appearing in the first place as an ill-defined 
accumulation of dark scales around the disco-cellular 
nervules, it takes the form of definite spots as the in- 
vasion of white or other pale ground tint progresses. As 
in the case of the other series, resolution is generally best 
marked in the males; the females showing a greater 
tendency to adhere to the ancestral condition. When 
fully resolved, the series consists of five spots, two for 
the disco-cellular nervules in the forewing, and one for 
the second disco-cellular in the hindwing, with two extra 
spots, also in the hindwing. In many instances the 
disco-cellular nervules, with a varying amount of neigh- 
bouring ground-substance, may appear as pale streaks or 
patches in the midst of the primitive agglomeration of 
dark scales; and in the further development of the 
pattern it may happen that either the pale or the dark 
markings alone persist; or both may be retained and 
worked up as in species of Colias, Callidryas, Ivias, etc., 
into a system of more or less elaborate ocelli. 
5. The markings on the underside of the hindwing. 
a. The yellow precostal streak.—A. constant feature in 
our common species of whites is a deep yellow or orange 
streak which occupies the margin of the precostal space 
on the underside of the hindwing, and is clearly dis- 
tinguishable from the pale yellow of the general ground- 
colour. This yellow precostal streak is conspicuous in 
other species of Ganoris, as G. gliciria, and may also be 
seen in S. daplidice, S. hellica, and many other members 
of the genus Synchloe. It is, I believe, never found in 
Pontia crategi; in the closely allied P. hippia and P. 
