NO. 2 HONEY BEE — SNODGRASS 71 



is termed by Duncan (1939) the "mesosternal retractor of the 

 propectus." 



The coxae of the mesothorax are elongate and semicylindrical in 

 form; each is attached by the entire length of one side to the under 

 surface of the thorax behind the mesosternum, and the trochanter 

 arises from its mesal end (figs. 15. 22 A, B). The mesocoxa is 

 definitely hinged to the body between a lateral pleural articulation 

 and a mesal sternal articulation (fig. 16 F) ; its axis of movement is 

 obliquely transverse, with the mesal end somewhat in advance of the 

 lateral end, and its movement is rotary on the axis. 



The musculature of each middle coxa comprises two promotor 

 muscles inserted at opposite ends of the coxa anterior to the axis of 

 rotation, and two remotors with the same distribution behind the 

 axis. The lateral promotor (fig. 22 C, 80) is a long muscle arising 

 dorsally on the small pleural apophysis {PI A) of the mesothorax, and 

 inserted on the anterior coxal rim a short distance from the pleural 

 articulation {d). The small mesal promotor {81) arises ventrally on 

 the median plate of the pterothoracic endosternum, and is inserted on 

 the anterior coxal margin near the sternal articulation {e). The 

 lateral remotor of the mesocoxa {82) is the muscle of the subalar 

 epipleurite {Sa) ; it arises by a broad base on the posterior margin of 

 the coxa just behind the pleural articulation, and is inserted by a long 

 tendon on the subalare. This muscle probably has little effect as a 

 motor of the coxa, but it would appear to be primarily a pleurocoxal 

 muscle. The mesal remotor of the coxa (<?j) is the largest of the 

 coxal muscles ; it arises on the median plate of the endosternum and 

 is strongly attached mesally on the posterior coxal margin. 



The metathoracic coxae (fig. 15) are hinged obliquely transverse 

 between pleural and sternal articulations (fig. 16 F), as are the 

 mesocoxae, but their bases are more nearly horizontal than are those 

 of the latter, and the coxae themselves project posteriorly (fig. 24 A), 

 with the trochanters arising from their distal ends. 



The musculature of the metacoxae is the same as that of the 

 mesocoxae, there being inserted on the base of each hind coxa four 

 muscles (fig. 24 B), two of which, attached before the coxal axis 

 {d-e), are, the one a lateral promotor (-foj), the other a mesal pro- 

 motor (104), while a third inserted mesally behind the axis is a mesal 

 remotor (106). The fourth muscle (io§), as in the mesothorax, is 

 the coxosubalar muscle of the wing; it is attached on the coxa so 

 close to the pleural articulation (d) and so nearby on the line of 

 the coxal axis that it can have little effect as a motor of the coxa. 



