72 KANSAS UNIVERSITY QUARTERLY. 



specialization of the scales for strength, as previously pointed out. 

 But the scale-covering of the forewings of these patterned forms is 

 more specialized than that of the forewings of certain other Arctians 

 which do not exhibit a considerable degree of color-marking, as 

 EucJucies, where the forewings are of uniform dull-grayish color. 

 Now the specialization of the wings for flight (shown by venation) is 

 practically the same for these two Arctiid genera, so that the increase in 

 specllization of the scales of the forewings of Halcsidota and Arailinis 

 over the condition shown by EucJuetcs is to be correlated with the 

 patterns and color-markings of the first two examples and the absence 

 of such markings in Eiicluetes. 



Again, the hindwings of Euprcpia and Epicallia show vivid and 

 sharply defined color-markings; and correspondingly the scale-cover- 

 ing of these wings is more specialized than the scale-covering of the 

 hindwings of Halesidota argentata which are not patterned. This 

 difference of scale-specialization among these related forms is evi- 

 dently to be correlated with the color-function rather than with the 

 strengthening function of the scales. 



Among the butterflies, who when at rest hold their wings together 

 over the back so that the under sides of the wings (chiefly of tlie 

 hindwings) show, the under sides of the wings present distinctive and 

 complex color-markings, the pattern of the under side of the hind- 

 wings being often more elaborate than that of either surface of the 

 forewings.* There is correlated with this a condition of wing- 



*Aa excoUent exanipl" nf tlu^ clTective iiiarl^inc;- of thi' uiulei- sides of the wings is shown 

 by Argynnis neraili //.>-■/■-■ //" '/'///. The upper sides of the wiugs are patterued in black and 

 brown according t" t lie t;iiiilli;ir Avgyuuid type. When the insect is flying, this bJack and 

 brown pattern eoiistii nte-^ the eliiet visible coloration of the butterfly. On the under 

 side of thehindwhm the in-uwn m-oiiini i~ -^ sufftised with greenish as to be practically mot- 

 tled pale green: tliere arealso u.:- uMial a rue silvery spots or blotches. A similar greenish 

 "round with smaller hilver^• sp(ii> (neui>, on a considerable triangle at the apex of the 

 forewnig (under sidei and the greenish extends along the costa to the base of the wing, 

 and along the outer margin to the anal angle. The rest (the disc) of the wing is brown 

 and Idaek niueh as on the upper sides of the wings. When the wings are folded above 

 the body, uiiper sides opposed, the hind wing covers all of the brown and black space of 

 the und'er side of the forewings but doer- not inv;T The apex, the eosta and the outer mar- 

 gin which are greenish: so that when i in- lnp ; ••rii.\- is ai i-est w ii li its wiiius foliU'd the 

 entire visil>le ixn-tion of the wings is a li-i 1,1-1 1 -rcuiid with silvery spots, quit 1^ ;i differ- 

 ent color and iiiittern from that present <-M i.y ihc ilyiuu iii>t .-l, Imii one un(loul)tedly much 

 more in bariiionv witli its ten-eslfial siifi-umi,lin,-s. Tlw iiuei-estiii);- tlnim' in the case 

 is that .inlvtlial iiort ion ot thr utKlrf -ide ..r the f'.fewiiiu- whieli is I'xp.ised when the 

 wings are fuliled lias acMUired 1 he ur'-r'nisli L;r(.tiiid: the part of the snfr:ii-e unexposed 

 possesst-s a, e<dor aiiil paricrn likfiliat i.l t lie upper sides of the wings. Is the brown and 

 lilack the tirst a,e(|u;icd cnioi- :ind pattern:- It is plain that selection would have no 

 tendency to ehanue the eoh.r of ihis iim-xposed part of the wing surface, and this color, 

 thus, pr'oliably repivsenis the m-iginal t'olor and pattern of the whole under side of the 

 wing It also adds lo the general brown and black effect of the flying insect that this 

 considerable portion of the under surface of the forewiug is brown and black: while it 

 would not at all add to the greenish and white effect of the motionless insect if this 

 portion were greenish and white. 



A similar distinctive ;ui(l striking coloration of the undersides of the wings is shown 

 by I'ierisbK-kni. a inoitniain Pierid first taken in Virginia City, Nevada, on flowers o*" 

 Brassica. Th; winus ai-,' mostly white above, with a few black spots, mostly gathered at 

 the apex of the lorewing. The uurier side of the hindwing has a white ground with many 

 ra.ther elongate rectangular spots of greenish, the greenish color coverin-- in.nedf the 

 wing-surface thtm the white. The apex and outer margin of the under side..; 1 in- f.. re wing 

 is niarked as the hindwing. while the disc is white with a hlack spot. When tiu' imtterfly 

 is at rest the color effect is yoUowish-green modified by white, a coloration proljably 

 effectively protective. The white disc with black spot on the under side of tlie forewing 

 is concealed when the .butterfly is at rest, and therefore does not share the otherwheres 

 general greenish color of the under sides of the wings. 



