MAYER: COLOR AND COLOR-PATTERNS. 
297 
many other cases the outer black and middle black are completely 
fused, so far as the upper surface of the wings is concerned ; but, 
if one examines the under surface of the hind wings, it will be 
found that a narrow rufous streak still persists between the middle 
black band and the outer black margin of the hind wing. 
(8) Variations of the Marginal Spots of the Fore Wing. The 
marginal spots are found very near the outer margin of the fore 
wing; they are usually either yellow or white, but in some few 
cases they are rufous. It appears from Table 9 that they are 
present in 146 and absent in 254 species of the 400 Danaoid Heli- 
conidae knoAvn to me. Fig. 101, Plate 10 , shows graphically 
the manner in which these spots occur in those species which 
possess them. It is evident from this curve that the number of 
these spots is not determined merely by chance, for they show a 
marked tendency to appear either as 2 or 3, or as 6 or 7 spots. 
It is due to this fact, that there are tAVO maximum points upon 
the diagram Fig. 101, Plate 10 . In those species which exhibit the 
“ 2- or 3-spot ” condition, the spots are found near the front apex 
of the fore wing. In the “ 6- or 7-spot” condition they lie all along 
the outer margin of the fore Aving, one spot in each cell. In the 
genera Ithomia, Napeogenes, and especially in Ceratinia these mar¬ 
ginal spots have become large and conspicuous ornaments. (See 
Fig. 49, Plate 4 .) 
Table 22 shows the manner of appearance of these spots in the 
genera Heliconius and Eueides. They are found in only 26 species 
of the 129 known to me ; and this number is far too small to war¬ 
rant general conclusions concerning the order of their appearance. 
(9) The Marginal Spots of the TIind Wing. Table 14 illus¬ 
trates the manner in which the marginal spots of the hind Avings 
make their appearance. They are absent in 279 and present in 
121 of the 400 species of the Danaoid group. Thus they occur 
rather less frequently than the marginal spots of the fore wing. In 
the 121 species in wdiich these spots are found they show a decided 
tendency to appear either as 4 or as 5 spots. Fig. 102, PJate 10 , 
is a graphic representation of the distribution of these spots, derived 
from Table 14. It appears that the outline of the figure approaches 
a probability curve, and is approximately symmetrical about the 
mean ordinate (A, B), situated at 4.54. 
