NO. 2 



HONEY BEE SNODGRASS 



17 



proximal end of the narrow mesal sclerite (e) of the stipes. The 

 lacinial sclerite serves in the bee as a lever for keeping the lobe erect. 

 On the upper point of its base is inserted a muscle from the stipes 

 (F, 16), the contraction of v^hich revolves the lever on its fulcrum 

 and thus exerts a tension on the lobe. The lacinial lobe is the "Segel- 

 halter" of Wolff (1875), v^^ho notes the lever sclerite in its base, and 

 terms its muscle the "Spanner des Segelhalters." The muscle repre- 

 sents the flexor of the lacinia in generalized insects ; the lever ap- 

 paratus is present also in other Hymenoptera. In Vespula (fig. 5 A, 



Ga 



Lo Ivr 16a 



Fig. 5. — Examples of the maxillary lacinia in Vespidae and Apoidea. 



A, left maxilla of Vespula macidata (L.), with well-developed lacinia, dorso- 

 lateral view. B, right maxilla of same, ventromesal view. C, detached lacinia 

 of left maxilla of same, lateral view, showing mesal lever arm {Ivr). D, base 

 of right maxilla of Bovihus americanorum (F.), with small lacinia attached to 

 large membranous area, mesal view. E, right lacinia and lever sclerite of 

 Xylocopa virginica (L.), mesal view. 



B, C) a small sclerite (Ivr) in the base of the lacinia, giving insertion 

 to the lacinial muscle (A, B, 16), curves around the proximal end 

 of the lacinia to articulate on the stipes (B). In Bombus (D) the 

 base of the lacinia itself articulates with the stipes, but in Xylocopa 

 (E) there is a distinct lever sclerite (Ivr) giving insertion to the 

 lacinial muscle (16). 



The minute, two-segmented palpus of the maxilla (fig. 3 A, MxPlp) 

 arises from the end of the stipes laterad of the base of the galea, and 

 is provided with a large muscle (fig. 4B) arising in the stipes 

 {¥,14). It is not evident why so small and seemingly unimportant 

 an organ should have a muscle of such size. Wolff (1875) believed 

 that the palpus muscle serves as an extensor of the galea, and Mori- 

 son (1927) regarded it as a muscle of the galea, which, he says 



