ELYTRA. 283 



they are thickened opaque plates, generally carried, when the 

 insect is not on the wing, in a horizontal position upon the 

 back, with the internal (or anal) margin (or suture, as it is 

 technically termed) straight, and in the direction of the mid- 

 dle line of the body. They are destitute of nerves, and are 

 internally lined with a thin membrane. As to their consist- 

 ence, they are variable, although generally very hard and 

 horny; sometimes even so firm as to be with difficulty 

 pierced by a pin. In other instances, however, they are flexi- 

 ble, or elastic, yielding to pressure ; and in others, even soft, 

 varying according to the variations in the consistence of the 

 body. As to their form, they are generally in the figure 

 of an oblong square, having the posterior angles more or 

 less rounded ; at other times they are more triangular, 

 oval, or even almost hemispheric. Sometimes they entirely 

 cover the abdomen ; at others they leave the extremity of 

 this part exposed ; and sometimes, as in the Brachelytra, 

 they are very short. As to their surface, they are flat, con- 

 vex, gibbose. They are also variable as regards their cloth- 

 ing; some being quite naked, others hairy, woolly, silky, 

 spiny, squamose, and rugose, like shagreen, or with impres- 

 sed or elevated spots, either placed irregularly (fig 133, o), 

 or disposed in lines (Lineato-punctate, fig. 133, x), or with 

 impressed lines (Elytra striata, fig. 133, f)- Their colours 

 are very variable, according to the habitation of the insect. 

 Thus beetles, living in dark places, under ground, and stones, 

 &c., are generally black, whilst those which are exposed to 

 the light are more variegated in their tints. As already ob- 

 served, these organs, during flight, are but little serviceable 

 as locomotive instruments ; and unless it were for the man- 

 ner in which they are carried at such times, it must be evi- 

 dent that, from their size and substance, they would neces- 

 sarily present a great obstacle against quick motion in the 

 air ; but this is provided against by their being carried either 



