48 KANSAS UNIVERSllY (QUARTERLY. 



perceptibly advanced beyond those of the other tier. The scales of the 

 upper tier alternate with those of the under tier, and each upper scale 

 overlaps laterally two under scales. In Morp/iothe upper scales over- 

 lapped the under scales but little; in Callidryas eiihiile two adjacent 

 upper scales covered fully two-thirds of the scale lying beneath and 

 between them; often the margins of the two adjacent upper scales 

 almost met along the median line of the under scale. In a Lyccenid 

 the upper scales overlapped about one-fourth the scale's width on 

 each margin; in Papilio troilus the overlapping was about the same; 

 in another Papilio the under scales were almost entirely covered. 



This arrangement of the scales is more 

 easily understood by reference to fig- 

 ures 2, 3 and 4. In addition to this lat- 

 eral overlapping, the distance between 

 the points of insertion of the scales 

 of one row and the points of inser- 

 tion of the scales of the row just in 

 front or just behind it is less than 

 the length of the scales, so that there 

 is an overlapping of the tips of the 

 scales of one row over the base of 

 the scales of the row in front (see 

 figs. 2, 3 and 4). By this double over- 

 lapping of the scales there is formed a 

 complete covering or sheet of scales over the upper and under sur- 

 faces of the wings, and often times almost a double sheath or covering. 

 The rows of scales on the under surface of the wing exhibit no 

 uniformity of relation with those of the upper surface, i. e., a row 

 on the under surface does not 



Part of wing (niauuitied) of Grapta 

 jnierragaiionis, shc.w rows ot insertion 

 cups on under and iipper surfaces. 





m 



have directly above it on the 

 upper surface a row in which the 

 scales are inserted at points 

 corresponding exactly in posi- 

 tion with the insertion points 

 of the scales of the under row; 

 nor is there a regular alternation 

 of rows. In fact, rows on the 

 lower side of the wing are but 

 rarely approximately parallel with 

 rows on the upper side. Figure 3 

 represents a portion of the fore 

 wing of Grapta interrogationis 

 denuded of scales but showing the rows of insertion cups of both 

 surfaces, the cups of the under side showing through. 





Fig. 4. 

 Part of wing of butterfly, magnifled, 

 sliowiug arrangement of the scales. 



