110 



THE DRAGON FLY. 



Fig. 129 6, side view of false gill, showing but one leaf), the 

 respiratory leaves, called the tracheary, or false-gills, are not 

 enclosed within the body, but form three broad leaves, perme- 

 ated by tracheae, or air-vessels. They are not true gilis, how- 

 ever, as the blood is not aerated in them. They only absorb 

 air to supply the tracheae, which aerate 

 the blood only within the general cavity 

 of the body. These false gills also act as 

 a rudder to aid the insect in swimming. 

 It is interesting to watch the Dragon 

 flies through their transformations, as 

 they can easily be kept in aquaria. Lit- 

 tle, almost nothing, is known regarding 

 their habits, and any one who can spend 

 the necessary time and patience in rear- 

 ing them, so as to trace up the different 



stages from the larva to the adult fly, and 13 - Pu pa of Cordulia. 

 describe and figure them accurately, will do good service to 

 science. 



Mr. Uhler states that at present we know but little of the 

 young stages of our species, but the larva and pupa of the Libel- 



lulas may be al- 

 ways known from 

 the .ZEschnas by 

 the shorter, 

 deeper and more 

 robust form, and 

 generally by their 

 thick clothing of 

 hair. Figure 130 

 represents the 

 pupa of Cordulia 

 lateralis, and fig- 

 ure 131 that of a 

 Dragon fly re- 

 ferred doubtfully 

 131. PupaofDidymops? to the genu . s 



Didymops. For descriptions and figures of other forms the 

 reader may turn to Mr. Louis Cabot's essay " On the Immature 

 State of the Odonata," published by the Museum of Compara- 

 tive Zoology at Cambridge. 



