514 THE BUTTERFLIES OF XEW ENGLAND. 



of pattern according as the break occurs in the interspaces or at the veins . 

 In the former case, the tendency of dark scales to chister along interrup- 

 tions of any nature in the surface, whether veins, folds, creases, or mar- 

 gins, together with the concentrating force presumed in a rupture of the 

 band, will be sure to cause the scales to collect along the veins, and, 

 vmiting with similar spots upon them, to border the vein on either side 

 continuously. This will map the veins very distinctly upon the ground, 

 producing in fact that condition of things which Mr. Higgins considers 

 the primary pattern, but which, certainly, we rarely find in moths and not 

 very commonly in the highest butterflies. Indeed, when carried to an 

 extreme, as in the dark-veined insects with otherwise diaphanous wings, we 

 find it only in some of the very highest moths (Aegerians and Sesiadae) 

 or butterflies (Heliconians). The junction of these darkened veins with 

 the darkened border of the wings produces, I suppose, the series of spots 

 upon the tips of the veins which sometimes occur there, but, as already 

 stated, on no other part of the veins. 



If, on the other hand, the break be supposed to occur at the veins them- 

 selves, then the tendency would be to form short transverse bars, or quad- 

 rate or more or less rounded spots in the interspaces ; and, finally, by a differ- 

 entiation of the exterior and interior portions of a round spot, a more or 

 less perfect ocellus would be formed. Occasionally we find long streaks of 

 dark color down the middle of the interspaces, similar to those along the 

 veins, produced, no doubt, by the frequent presence of a crease in such 

 places, and the tendency of scales to follow it ; the comparative weakness 

 of such breaks in the continuity of the membrane is the reason of the com- 

 parative rarity of this form of ornamentation. The formation of ocelli has 

 been shown by Darwin, who traced, in specimens of a South African but- 

 terfly (Cyllo leda) a perfect gradation "from excessively minute white 

 dots, surrounded by a scarcely visible black line, into perfectly symmetri- 

 cal and large ocelli" ; and instances are common in our own butterflies 

 where one can follow a similar series onward from a uniform circular dark 

 spot. First, a central white dot appears in it ; next the whole is encircled 

 by a light-colored halo, and so on. Darwin mentions one moth with a 

 magnificent ocellus consisting of a black centre with eight concentric zones 

 of colors. 



Ocelli not infrequently surpass the bounds of the interspace in which they 

 originate, but among the hundreds of ocellate specimens examined with 

 this point in view, I have failed to find a single ocellus of a simple charac- 

 ter which could not be definitely referred to some particular interspace. 

 But there are other ocelli, of a complex character, such as those of the 

 peacock butterfly of Europe (Inachis io), where, assuming it had a similar 

 origin, we cannot possibly say where it belongs ; but in this butterfly, the 

 other markings of the wing are seen directly through the ocelli, as through 



