RISE AND PROGRESS OF ZOOLOGY. lxVll 



edition of the Sy sterna, the number of pinnal rays 

 is most insisted on. 



The fifth class of Insects is subdivided into 

 seven orders, the characters of which are mostly 

 taken from the differences observed in the num- 

 ber and texture of the wings. 



Order I. — Coleoptera. Wings four, the 

 upper two crustaceous, divided by a straight 

 suture. 



Order II. — Hemiptera. Wings four, upper 

 two semi-crustaceous, incumbent on each other 

 at the inner edges. 



Order III. — Lepidoptera, Wings four, all of 

 them having imbricated scales. 



Order IV^-Neuroptera. Four wings, all of 

 them membranaceous ; no sting. 



Order "V '.—Hymenoptera. Four wings, mem- 

 branaceous ; stings, but only in the females and 

 neuters. 



The generic and specific characters are 

 drawn from different parts of the body, and 

 from so prodigious a variety of circumstances, 

 that we cannot think of entering even on the 

 slightest detail of them. 



The sixth class, Vermes, is divided into 

 five orders. 



