464 NORTH AMERICAN DIPTERA 



Collatia, new genus 



Tliis genus is proposed for the reception of ZeniUia siihmissa 

 Aldrieh and Webber. It possesses the characters of ZeniUia but has 

 the propleura haired on the middle portion. 



Townsendina, new genus 



Differs from Myiophasia Brauer and Bergenstamm in having only 

 one pair of presutural acrosticals and long, bristly hairs on the para- 

 facials. Front narrow above, widening anteriorly; cheeks half as wide 

 as the eye-height; antennse reaching four-fifths the distance to the oral 

 margin, the second segment only one-third shorter than the third; arista 

 thickened on basal fourth; proboscis short; eyes short pilose. Dorso- 

 centrals 3-3; acrosticals 1-2; propleura bare; infrasquamal setula 

 present. Apical cell ending moderately before the wing tip; third vein 

 with two bristles basally. Abdomen with diseals and marginals. 

 Thorax cinereous pollinose, weakly vittate; abdomen with broad, basal 

 cinereous fasciae on segments two to four. Genotype : — T. fasciata, 

 n. sp., (Colorado). 



Polidaria, new genus 



Proposed for Tacliina arcos Walker, a species placed in the genus 

 Polidea by most authors. As it does not belong to Polidea, a new genus 

 is proposed for its reception. 



Zonalia, new genus 



Female. — Head short, almost twice as high as long; two pairs of 

 proclinate frontals; ocellars short; outer verticals absent; cheeks nar- 

 row; face slightly retreating below; facial ridges with Aveak bristles 

 on the lower half; antennae reaching to the oral margin; arista long 

 plumose. Acrosticals 1-0; dorsocentrals 2-3; one sublateral; posthumeral 

 absent; i)ropleura bare; infrasquamal setulas present; two sterno- 

 pleurals; prosternum bare; three pairs of marginal scutellars. Anterior 

 tibiae with one posterior bristle. Apical cell ending close to the wing- 

 tip; third vein bristled more than half way to the anterior crossvein. 

 Abdomen without diseals; first segment without marginals; ovipositor 

 normal. Front, thorax and sides of abdomen with whitish pollen, al- 

 though the whole insect appears shining black from most views. Length, 

 5 mm. Genotype: — Z. nitens, n. sp. (Panama). 



