M:iy— June iSS^J 



PSYCHE. 



45 



Miul tliL- brown scales have the same form 

 and structure, and both cont.iin air, as 

 can be readily seen by the action of water 

 upon them. Neither the brown nor the 

 yellow scales can be bleached by chlorin. 

 Of the numerous scales of curculioti- 

 idac, the family of coleoptera in which 

 the possession of scales may be said to 

 be alnnst a rule, I haye chosen for es- 

 pecial study the 



SCALES OF ENTIMUS IMPERIALIS. 



This species has the most brilliant, 

 and, in some respects, the most interest- 

 ing- scales and hairs of any colcopteron 

 which I haye examined. Nearly its 

 whole suffice, above and beneath, is 

 covered with linjs or masses of minute 



Fii^. 1 1. Scales of Entimus imperialis: on a, b and c 

 vertical lines indicate blue, horizontal lines indi- 

 cate carmine red, and oblique lines yellow; where two 

 kinds of lines cross, one color is tinged with the other; 

 on (/ and c the fine lines represent the finer striation of 

 the inner layer of the scales. Enlargement : d, b and f, 

 ino diam. ; d and c, 300 diam. 



scales, glistening by reflected light with 

 the brightest colors, and these colors are 

 heightened by the shining black back- 

 ground which the surface of the insect 

 affords. Hairs and scales cover its legs, 

 and the hairs, as will be seen later, are 

 of the same nature as are the scales. 



The form of these appendages is 

 extremely variable. Their greatest 

 width is about 0.06 mm., and from this 



width gratlations may be foinid down 

 to hairs of a diameter of less than o.oi 

 mm. Tiie length of such as are typi- 

 cally scales (fig. II. a. b and c) is 0.15 

 to o. iS mm. The hairs attain a length 

 of 1.3 mm. 



Both hairs and scales :ire colored in 

 the same way and with the same colors, 

 chiefly red, blue and yellow, by trans- 

 mitted light, and green and purple by 

 reflected light. Whatever the color by 

 reflected light, its complementary color 

 appears by ti'ansmitted light ; predomi- 

 nant is red bv transmitted, and green 

 by reflected light. Thus one sees the 

 origin of the green color on the colco- 

 pteron itself. Green, yellow, red, blue 

 and purple often appear on a single 

 scale, and these colors change if the 

 light is clianged from transmitted to 

 reflected ; they are especially bril- 

 liant upon a black background. .Some 

 scales are of a single color, usually red. 

 On figure 11, a, h and c, I ha\'e at- 

 tempted, as far as is possible without 

 colored figures, to show the distribu- 

 tion of colors in three scales. Even 

 colored figures would have poorly re- 

 presented some of the brilliant variations 

 which the scales present. 



More careful miscroscopical exami- 

 nation sufficed, even with low powers, 

 to show that the scales have the ap- 

 pearance of being filled with pig- 

 ments, separate colors usually in dis- 

 tinct compartments allotted to them. 

 Sometimes, however, similar colors, 

 like yellow and yellowish red (see basal 

 part of fig. II, rt), or like blue and 

 purple, are in the same compartment. 

 Sometimes there is a tinge of color near 



