26 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, IO3 



however, depend on the obliquity of lines of bending at the ends of 

 the palpiger (B, a-c, b-c, and b-d). 



The movements of the palpiger can be well illustrated with a piece 

 of stiff paper cut into the form shown at E of figure 8 and creased 



Fig. 8. — The labial palpus. 



A, right palpus, palpiger, and prementum, mesal view, showing muscles. 

 B, base of palpus in position of extension from prementum. C, same, palpus 

 flexed. D, base of palpus, posterior view, showing elastic rod (n) in posterior 

 wall of palpiger, and attachment of flexor muscle tendon. E, F, diagrams of 

 flexing of palpus on prementum, illustrated with piece of paper cut and creased 

 as at E, and folded as at F. 



a-c, b-d, lines of folding at ends of palpiger; b-c, line of diagonal folding of 

 palpiger ; b-e, line of infolding at base of flexed palpiger ; /, distal point on 

 palpus ; n, elastic rod in posterior wall of palpiger. 



along the lines a-c, b-c, b-d, and b-e. By folding outward along the 

 diagonal (b-c) through the "palpiger" the triangle abc is turned over 

 and directed downward (F) ; the "palpus" can now be bent backward 

 in a horizontal position, but its alignment with the "prementum" 

 necessitates a compensating fold inward along the lines b-d and b-e. 



