NORTH AMERICAN DIPTERA. 



329 



structure of the sensitive portions of the terminal joint is shown at 

 a, and consists of a series of fleshy tubercles on a membranous base, 

 the tubercles all furnished with rather stiff hair. 



Fig. 8. Mouth parts of £rax sp. 



At b, is shown the structure of the palpifer and palpus, the latter 

 single jointed and showing the same tendency noted in Tahanus. 

 At d, is shown the labium, the ligula central, not easily separable 

 trotii the paraglosste, wliich very evidently show their paired character 



in this species. 



In Asilus sericeus, fig. 9, the galear de- 

 velopment is cut away, and we note the 

 relative position of the parts. We notice 

 here, too, what is of some importance, that 

 the lacinia are reduced in size and really 

 rudimentary, thus forming the interme- 

 diate step to Stomoxys and Hcematobia, 

 where it is entirely wanting. So, also, the 

 galear structure reminds one strongly of 

 Stomoxys, especially in the structure of the 

 tip. 



Of other piercing species I will call at- 

 tention only to the mosquito. This un- 

 fortunate insect has been the subject of so many figures that I will 



(42) NOVEMBER, 1890. 



Fig. 9. Mouth parts of Asi7» 

 sericei4s. 



TRANS. .\M. ENT. SOC. XVII. 



