IN SECT A. 13 



In accordance with the plan heretofore pursued, 

 and which we think presents certain advantages, we 

 shall now describe the regions of the body, neglecting 

 for the present all the appendages. In considering 

 these regions it is better to begin with the head (PL I., 

 Figs. 2, 3, ^ ; Fig. 4), as by so doing the distinctive 

 features of the Insecta are brought out more clearly. 

 This part is long and narrow in shape and is set at 

 right angles upon a fleshy neck, so that it moves freely 

 upward, downward, and sideways. It is marked by 

 sutures, but no inference as to the number of rings 

 composing it can be drawn till the number of append- 

 ages has been determined. 



The epicranium (PI. I., Fig. 4, ep) extends from the 

 upper part of the head to the broad, short, immovable 

 plate or clypeus {cl) below; the gena, or cheeks {gn), 

 occupy the sides of the head. 



The forward part of the thorax is known as the pro- 

 thorax (PI. I., Figs. 3, 7, ^' ; Fig. 7, side view of 

 Caloptenus spretus). The dorsal and lateral portions 

 form a cape which extends backward from the neck, 

 and is free along its posterior margin. There is a slight 

 longitudinal ridge through the middle, and it is marked 

 by three distinct grooves, which divide it into four 

 parts. 



PL I., Fig. 3, t^ is the scutum, ts^ the scutellum. The 

 part in front of the scutum is the praescutum, and that 

 back of the scutellum the postscutellum. These two parts 



but we should not blind ourselves to the more obvious relations 

 of both groups, as members of the Articulata or segmented 

 animals. 



