290 BULLKTIN 31, UNITED STATES NATIONAL MUSEUM. 



terioily by the posterior basal cross-vein, posteriorly by the sixth lon<jitudinal. The 

 first posterior cell is bounded in front by the third longitudinal, behind and exteriorly 

 by the ultimate and penultimate sections of the fourth vein, internally by the 

 anterior cross-vein. The discal cell is inclosed in front by the fourth longitudinal, 

 behind by the fifth longitudinal, exteriorly by the posterior cross- vein, internally by 

 the anterior basal cross-vein. The third posterior cell lies between the fifth longitu- 

 dinal and the posterior basal cross-vein. 



Stigma. — A colored spot near the tip of auxiliary vein. 



VESTITUKE. 



Pile. — This term properly should be restricted to thick, fine, short, and erect hair, 

 as in the pile of velvet ; in reality, however, the word is incapable of definite limita- 

 tion, and is here generally employed, the word hair being only used to express very 

 sparse or coarse pile, as in the hair of the face in Chilosia, or the sparse vestiture of 

 the eyes in Syrphus. 



Macrochoetce, or bristles, are only present in Chilosia, spp., Brachyopa, spp., Eugeni- 

 omijia, VoluceUa, spp., and Chrysochlamys, on the thorax, and in a few others on the 

 legs ; never on the head. 



Pollen, or dust, is that Avhich conceals or obscures the shining or opaque ground 

 color to a greater or lesser degree, and is more or less easily removed by moisture or 

 nibbing. 



Tomentum primarily indicates short, flattened, appressed hairs, and is only found in 

 Lepromyia, Myiolepta, sp., though in some other cases the term is used to designate 

 coarse pollen, as in Temnostoma. 



Pubescence is here used only to indicate very short, nearly microscopical hairs, on 

 the arista, wings, etc. 



