188 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
might lead one to infer that the ocellus of the fore wing was of the 
same character is, that an aberrant form is sometimes found in 
nature having the “eye-spots” on both fore and hind wings 
obliterated, thus indieating a possible connection between the two 
(see South, ’89). 
Fig. 18 is intended to illustrate the process of degeneration occur- 
ring in bands. Band BB is represented as hreaking down by the rare 
method of parting in the middle. Example, Melinaea parallelis. 
Band EE is degenerating at one end; this is a very common 
method. 
Figs. 20-23 represent hypothetical conditions not found in nature ; 
all being contrary to the conditions of the laws which have just been 
stated. 
In Fig. 20 row RR presents three spots for each cell. I believe 
this has not been found in nature, but I should not be surprised if 
it were discovered, for it is not contrary to any of the laws. 
Row CC, on the other hand, is contrary to the law of bilaterality, 
the erescents not being bilateral about axes passing through the 
middle of the interspaces parallel with the longitudinal nervures. 
Fig. 21 is intended to show a series of spots arranged side by 
side in twos in each cell, and of different colors. This, I believe, is 
impossible, for it is contrary to the law of bilaterality of color 
arrangement about the usual axis (HH, Figs. 6, 7). 
In Fig. 22 there are several conditions which are impossible; e. y., 
an eye-spot situated upon à nervure is never seen in nature, also 
two spots originally side by side, as in cell III, never rotate around 
each other so as to come to lie one above the other. Spots often 
move, however, as shown by the arrows in cell IV, thus giving 
rise to fusions; or they may move away from each other, causing a 
wider gap between the rows. In cell I" are shown two looped 
spots. One form (A) is quite usual, being found indeed in Cymo- 
thoe caenis Drury.! The other form of spot (D) is an impossibility, 
not being bilaterally symmetrical. 
Fig. 23 illustrates other impossibilities in color-pattern, none of 
them, of course, being found in nature. For example, one never 
finds a row of slanting spots such as SS. Also one never sees a 
row of similar spots in alternate interspaces, such as is shown in 
DD, for this would be contrary to the law that similar spots are 
repeated in a row of adjacent interspaces. These last four diagrams 
1 See Cramer (1779-82), Vol, 2, Plate 146. 
