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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 23 



Fig. 9. — The larval abdomen, Anax Junius (Drury). 



A, entire abdomen, ventral. B, segments IV, V, and VI, showing diaphragm 

 and transverse muscle, with associated parts of alimentary canal and tracheal 

 trunks, ventral. C, dorsal and lateral muscles of a typical abdominal segment, 

 ventral. D, E, small outer muscles on sternal and tergal plates of larval abdo- 

 men (from Whedon, igi8). F, cross section of a middle segment of abdomen, 

 showing position of muscles. G, same segment contracted as in expiration during 

 mild breathing. H, same segment contracted as in stronger expiration. I, an 

 abdominal sternum, showing its three parts. J, sides of first three abdominal 

 segments. 



de, external dorsal muscles ; di, internal dorsal muscles ; Dph, diaphragm ; 

 dTra, dorsal trachea ; lo, oblique lateral muscle ; 1st, laterosternite ; Iv, vertical 

 lateral muscle; Mai, Malpighian tubules (cut off) ; Mcnt, mesenteron (ventric- 

 ulus) ; mst, mediosternite ; rspC, respiratory chamber; St>, spiracle; tmcl, trans- 

 verse muscle ; v, ventral muscles ; vTra, ventral trachea. 



