NO. 2 HONEY BEE^ SNODGRASS 25 



the posterior part of the tongue in the ample membrane of the glossal 

 channel, the contractile and flexible tongue is not only shortened by 

 the retraction of the rod, but is sharply curved in a posterior direction. 

 Thus the retraction of the proboscis by the retractor muscles of the 

 labium effects also the retraction of the base of the ligula into the 

 prementum, and the latter action produces automatically the shorten- 

 ing and posterior flexion of the tongue. The salivary syringe also is 

 pulled inward by the inflection of the ligular arms, and in the re- 

 tracted condition its muscles are slack and temporarily functionless. 

 Inasmuch as there is no muscular mechanism for the protraction of 

 the ligula, it must be assumed that the parts are extended by the 

 elasticity of the inflected ligular arms and the subligular plate when 

 the retractor muscles relax. 



The long, 4-segmented labial palpi (fig. 8 A) arise from the distal 

 end of the prementum, where each palpus is supported on a small 

 basal lobe (Pig) commonly regarded as being a palpiger, i.e., a palp- 

 supporting lobe of the prementum, rather than a basal segment of the 

 palpus. In nonconformity with this idea, however, the single muscle 

 of the palpus (^i) is attached within the basal lobe. The palpus itself 

 contains only one muscle (22), which arises in the long first segment 

 and is attached mesally on the base of the succeeding segment ; it flexes 

 the distal part of the palpus, which, when released, springs back to 

 the extended position by its own elasticity. 



The flexing mechanism of. the entire palpus, by which the palpus is 

 turned back behind the prementum when the proboscis is retracted, 

 is in the small palpiger. Each palpiger is flattened from side to side, 

 and its walls are membranous except for a narrow sclerotic bridge 

 in the anterior wall, which connects the first palpus segment with the 

 prementum (fig. 8 A), and a slender, flexible and elastic rod in the 

 posterior wall (A, D, n) that is continuous from the prementum to the 

 midrib of the palpus. The basal muscle of the palpus (B, 21) is 

 attached by a long tendon on the posterior rod a little beyond the 

 middle of the latter. When the palpus is extended (B) the rod is 

 slightly curved into the rear wall of the palpiger ; when artificially 

 flexed (C) the palpus is turned back with its lateral surface posterior, 

 and the elastic rod of the palpiger (m) is strongly curved into the 

 posterior wall of the palpiger. There can be little question, therefore, 

 that the flexing of the palpus results, conversely, from an incurving 

 of the rod by the pull of the muscle attached on it, and, in fact, the 

 action can be demonstrated in a dead bee by pressing the rod so as 

 to bend it into the palpiger. The exact movements of the palpus. 



