58 KANSAS UNIVERSITY QUARTERLY. 



The transition from simple hair to broad, flat scale is easily 

 observed, a long and interesting series of gradatory forms being 

 obtainable sometimes from a single moth. The transition most com- 

 monly occurs by (a), the slight thickening and widening of the 

 distal portion of a hair; (b), the dividing, or apparent splitting of the 

 thickened distal portion into two, three or more branches or fingers, 

 lying in one plane; (c), the gradual shortening of the proximal or 

 basal portion of the scale-hair, accompanied by a widening and 

 " filling in " between the bases of the fingers. This palmation may 

 extend almost or quite to the tips of the fingers, or the fingers may 

 remain as long as the rest of the scale, or longer. There 

 is thus produced a flat scale with more or less shortened pedicel (the 

 proximal end of the hair) and with its opposite (outer) margin entire 

 or two- to several-pointed, the points being of greater or less length. 

 The longitudinal striae are apparent with the first widening of the 

 hair. 



This transition is well shown on the wing of Megalopyge, a genus 

 presenting probably the most generalized condition of scale covering 

 yet found by me in the Lepidoptera (see fig. 10, p. 54). 



Variations from this method of transition occur, as shown in a 

 discussion of the lines of specialization of the scales {posteci) but 

 all begin from a long, slender, hair-like form. 



In searching for the beginnings of the Lepidopterous scale, an 

 inspection of certain groups of insects whose phylogenetic relations 

 with the Lepidoptera are an interesting entomological problem, 

 presents some most interesting and suggestive conditions. An 

 inspection of the wings of the Trichoptera reveals a wing-covering of 

 the following character: a uniform covering of very small, slightly 

 curving, pointed hairs, firmly attached to the wing-membrane and not 

 inserted in a socket or cup; and also a varying covering of long, 

 usually striated, more or less flattened scale-hairs distinctly set in 

 insertion cups, and showing a more or less distinct, unstriated pedicel, 

 and not firmly attached to the wing (see fig. i, Plate IX). The fine 

 fixed hairs vary in length somewhat in different species, but are always 

 much shorter and more numerous than the scale-hairs. The scale-hairs 

 usually plainly indicate their scale condition, being often flattened, 

 regularly striated, and possessing a distinct pedicel. A Sctodes sp. 

 presents the following characters in the wing-clothing: the fine, fixed 

 hairs are about .008 mm. in length, and are situated about .007 mm. 

 apart. The scale-hairs vary from hair-like structures to flattened scales, 

 about .07 mm. to .10 mm. in length and about .008 mm. in width, 

 bearing uniform longitudinal stria; .0016 mm. apart. The pedicel is 

 distinct from the scale-blade, and presents a slight expansion near its 



