ARTHUR DEWITT WHEDON 435 



EXPLANATION OF PLATES 

 All figures drawn to measurement or under the camera lucida by the author. 



Plate XXI 

 Structure of the Larvae: Zygoptera 



P'ig. 1. — Levies U)i.guiculalus d^ opened donsally and spread out, showing the 

 muscular, nervous, digestive and respiratory systems. (X 8) 



Fig. 2. — Lesles unguiculalus 9 showing the visceral sheath, part of the diges- 

 tive tract and the ovaries in dorsal view. ( X 8) 



Fig. 3. — -Lcstes unguiculalus: dorsal view of the male reproductive organs of the 

 full grown larva. (X 8) 



Fig. 4. — Helaerina arnericana, showing the muscles of the left side of the first 

 three segments. ( X 8) 



Plate XXII 

 Structure of the larvae: Aeshnidae and Libellulidae 



Fig. 5. — Anax Junius cf with dorsum removed to show the main tracheae and 

 the digestive tract. Parts covered by others are indicated in 

 dotted lines. (X 4) 



Fig. tj. — Anax junixis d^ showing a lateral view of segments five to nine: ali- 

 mentary canal, dorsal tracheal trunk, transverse muscles, and 

 reproductive organs of the right side. ( X 4) 



Fig. 7. — Sympelrwn vicinum: half grown larva sectioned longitudinally ta 

 show the complete course of the alimentary canal. (X 7) 



Plate XXIII 



Structure of the larvae: Aeshnidae 

 Fig. 8. — Anax Junius 9 with dorsum removed to show the nervous and 



muscular systems. Most of the muscles of the left side have 



been dissected away to show the smaller sets. (X 4) 

 Fig. 9. — Anax Junius 9 . A cross section of segment six, viewed from the 



posterior end and showing especially the relations between the 



various sets of muscles, the alimentary canal, and the main 



tracheae. Camera lucida. (X 4) 

 Fig. 10. — Anax Junius 9. Longitudinal section showing the muscles of the 



right side, segments five, six and seven. Camera lucida. (X 4) 

 Fig. 11. — Anax Junius 9 • The tergum removed from the specimen figured in 



8, showing the muscles and heart. The larger muscles have, also, 



been dissected off to cxpo.se the smaller ones lying dorsallj'. 



(X 4) 

 Fig. 12. — Anax Junius. A diagram to indicate the relative positions of the 



sternal muscles. 



TRANS. AM. ENT. SOC, XLIV. 



