470 NORTH AMERICAN DIPTERA 



segment with marginals but without discals. Black with cinereous 

 pollen; palpi yellow; sides of the abdomen broadly reddish on the 

 basal half, the apex also reddish; pollen of front rather golden, of 

 mesonotum more or less ochreous and strongly vittate; apices of abdo- 

 minal segments broadly bare. Length 8 mm. Genotype : — A. lateralis, 

 n. sp. (Panama). 



Shermanalia, new genus 



Male. — Arista long plumose; front moderately narrow; ocellars 

 long; outer verticals absent; cheeks one-third as wide as eye-height; 

 face scarcely retreating, the oral margin prominent, the ridges bare; 

 apical section of the proboscis as long as the head-height; palpi 

 somewhat clavate; antennge not reaching to the oral margin, the second 

 segment short. Acrosticals 1-1, the anterior pair weak; dorsocentrals 

 2-3; posthumeral and posterior sublateral absent; sternopleurals 2-1; 

 prosternum bare. Apical cell almost closed a little before the wing-tip; 

 third vein with two weak bristles basally. Abdomen elongate, more 

 than twice as long as wide, rather cylindrical, all the segments with 

 marginals but without discals. Black, clothed with thick yellowish 

 pollen; mesonotum with three black vittas, the median one wide; first 

 ;ibdominal segment with an hourglass-shaped black spot, the base black, 

 the following segments broadly black apically, the black expanding 

 triangularly just below the sides. Length, 6 mm. Genotype : — S. pre- 

 tiosa, n. sp. (Panama). 



Prorhynchops errans Curran (fig. 172) traces to this genus but the 

 aristal rays arise from only the upper and lower surfaces. It is prob- 

 ably not a Prorliynclwps as it lacks discal bristles. 



Thelairalia, new genus 



Male. — Front rather wide, with a single pair of strong orbitals 

 ocellars short and hair-like; outer verticals distinct; cheeks narrow 

 face receding, the oral margin not produced; proboscis short; palpi 

 weakly clavate; antennas not reaching to the oral margin; arista very 

 short plumose. Acrosticals 8-3; dorsocentrals 2-3; posterior sublateral 

 poorly developed, the posthumeral absent; sternopleurals 1-1; pro- 

 sternum haired. Apical cell ending moderately before the wing-tip; 

 third vein bristled more than half way to the anterior crossvein. Abdo- 

 men tapering, each segment with marginals, only the fourth with discals. 

 Black, yellow pollinose: mesonotum with four vittee which unite to form 



