PSYCHE. 



THE SCALES OF COLEOPTERA. 



BY GEOKGK DIMMOCK, CAMHRIDGE. MASS. 



{Conthiited from page i/.) 



SCALES OF IIOPLIA. 



A few only of the scales from the 

 iipjjer side (jf this insect are colorless, 

 and, as these seem to be undeveloped 

 or immature, I tried no experiments 

 upon them. . 



The scales of the under side of H. 

 coerulca are purple, purplish red, red, 

 bluish and colorless by transmitted light, 

 and by reflected light thiy are silvery 

 white with a tendency to inetallic green 

 in places. The scales of the tip of the 

 abdomen, altho really doKsal in position, 

 are covered with spines, are mostl}' 

 reddish or purple by transmitted light, 

 and are metallic green bv reflected 

 light. Some of the scales of the leffs 

 arc like those from the rest of the under 

 surface of tlie insect : others of them 

 are lanceolate (tig. 3, c), and colorless 

 or milk-white, but covered with longer 

 spines or hairs than the more circular 

 forms of scales. The hairs of this in- 

 sect have line branches, as do the hairs 

 of all scarabaeidac. according to Fischer 

 and accortling to mv own oliscrvations. 



Water, alcohol, chlorf)form and simi- 

 lar reagents render the scales of the 

 inidcr side colorless and transparent, 

 the colors returning as soon as the 

 scales are dried. 



In flner structure the scales of the 

 under side are difl'erent from those of 

 the upper side in being clothed with the 

 before-mentioned spines or fine hairs, 

 and in the absence of tlie tine internal 

 network, which is here replaced in some 

 scales by a more iri'egular internal 

 marking of like nature. 



The scales of Hoplia modcsta, from 

 this country, are confined to the tip of 

 the abdomen and to the under side 

 of the insect. They are all gray or 

 milk-white by transmitted light, and 

 silvery by reflected light. They are 

 narrower than those from corresponding 

 parts of H. coern/ea. but are otherwise 

 alike in structure and need no further 

 mention liere. 



SCALES OF POLYPHYLLA. 



The wliitish spots upon the elytra of 

 Polyphylla variolosa are produced by 

 lanceolate scales, the opake whiteness 

 of which is caused by the large amount 

 of air contained in them. As they pre- 

 sent no characters of special interest not 

 to be found in scales of other coleoptera 

 described in this paper I have not drawn 

 them or further studied them. 



