188 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY, 



mifflit lead one to infer that the oceHus of the fore wingr 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 indicating 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 breaking 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 crescents not being bilateral about axes passing through the 

 middle of the interspaces parallel Avith 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. g., 

 an eye-spot situated upon a nervure is never seen in nature, also 

 two spots originally side by side, as in cell III, jiever 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 row^s. In cell P are shown two looped 

 spots. One form (A) is quite usual, being found indeed in Cynio- 

 thoe caenis Drury.i The other form of spot (D) is an impossibility, 

 not being bilaterally symmetrical. 



Fig. 28 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 14(5. 



