50 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



In Other words, both sets of wing movements are produced by primi- 

 tive muscles that have become motors of the wings by modifications 

 in the skeletal elements, the primary changes that made flight possible 

 being mostly in the thoracic skeleton, the secondary adaptations for 

 flexion and extension being largely in the bases of the wings 

 themselves. 



In the bee the principal muscles of llight are the huge longitudinal 

 and dorsoventral muscles of the mesothorax (fig. i6C). For this 



Fig. 18. — The wings. 



A, B, fore and hind wing of drone. C, hook of hind wing of worker. D, hook 

 of hind wing of drone. E, section of interlocked wing margins. 



/, deflected fold on posterior margin of fore wing; h, hooks on anterior 

 margin of hind wing. 



reason probably the two wings on each side, when extended, are 

 attached to each other. The coupling mechanism consists of a series 

 of small hooks on the anterior margin of the hind wing (fig. i8 B, h) 

 and a fold on the posterior margin of the fore wing (A, /). The 

 hind-wing hooks, or hamuli (C, D), curve upward and backward 

 from the marginal vein of the wing with a twist in the direction of 

 the wing tip. The fold of the fore wing is a rounded deflection of the 

 posterior part of the elevated wing area behind the last vein, and 

 has a narrowly upturned margin (E, /). When the wings are ex- 

 tended preparatory to flight the fore wing is drawn over the upper 



