LIBELLULID^E, OR DRAGON-FLIES. 155 



small insects. The eggs are deposited upon aquatic plants, and 

 the larvae are thus produced in the element in which they are at 

 first to reside. The head of the pupa is remarkable for the singu- 

 lar form of the portion which takes the place of the lower lip; this 



FIG. 471. LIBELLULA CANCELLATA. 



is a kind of mask, composed of several pieces, and covering the 

 mandibles, maxilla?, and nearly all the under side of the head, when 

 it is closed together ; but being capable of extension and unfold- 

 ing, and being furnished with a pair of sharp claws at its upper 

 part, so as to become the instrument by which the animal seizes 

 its prey. The posterior end of the abdomen, in the early state of 

 the Dragon-flies, is usually the seat of the respiratory function. 

 This is performed by means of three leaf-like membranous or- 

 gans, which are situated at the extremity of the abdomen, or by 

 the agency of tufted branchiae placed in the interior of the terminal 

 portion of the intestine. In the latter case the animal draws a 

 Supply of water into the rectum, and then forces it out violently, 

 by which act it also impels itself through the water. The suc- 

 cession of jerks thus produced, is the chief means of locomotion 

 of the larvae of many of the Dragon-flies, and serves to distin- 

 guish them from all other aquatic larvae ; so that they are very 

 easily recognised (Fig. 472). Several species of Dragon-flies 



