MOUTH PARTS OF THE NYMPH. 



the palp is not used as a scraper, the attachment is on the same side as the 

 insertion. 



V. Labium. 



Retractor. The retractor of the labium (PI. III. fig. 39. R) originates at 

 the base of the central plate of the tentorium, and is inserted at the lateral border 

 of the ligula (Lg) near the base of the paraglossa (Pgl). 



Adductor. The adductor of the labium (PI. Ill, fig. 39, ad) originates in 

 the submentum (Sm) near the median line, and is inserted in the proximal border 

 of the ligula (Lg). 



Abductor. The abductor of the labium (PI. Ill, fig. 39, Abd) originates at 

 the basal edge of the tentorium, and is inserted at the outer angle of the distal 

 border of the mentum (M). 



Ligula. 



Adductor. The adductor (Ad) of the paraglossa (Pgl) is attached at the 

 base of the ligula not far from the median line, and is inserted near the center 

 of the base of the paraglossa. The adductor (ad) of the glossa (gl) originates 

 in the central area of the ligula and is inserted at the base of the glossa. 



Labial Palp. 



Extensor. The extensor of the labial palp (PI. II'I, fig. 39, e) originates at 

 the central apodeme ( ap) and is inserted at the outer angle of the base of the 

 first palp segment. 



Flexor. The flexor of the labial palp (PI. Ill, fig. 39, f) originates at the 

 central apodeme (ap) and is inserted at the inner angle of the base of the first 

 segment of the palp. 



Within the palp, the extensors (e) arise on the outer side, and the flexors 

 (f) on the inner side of the basal angle, and are inserted into the outer and 

 inner side of the basal angle of the next distal segment. 



The exteme development of labial musculature is found among the 

 Heptageninae. The palp muscles are enormously increased in size and their 

 insertion shifted to give greater leverage. The extensor of the palp (e) of 

 Ecdyurus (PI. Ill, fig. 40) is inserted far out on the lateral surface of the basal 

 segment. It has no opponent. Within the palp the attachment of the flexor (f) 

 of the second segment extends across the base and along the outer lateral surface 

 of the first segment. The adductors (ad) and abductors (Abd) of the labium 

 are sheath-like bands extending across the fused ligula and mentum. Glossa (gl) 

 and paraglossa (Pgl) each possess one abductor (Abd) and two adductors (ad). 



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