hungerford: anatomy of simuliuai vittatum. 367 



Technically the adults of this family are distinguished by 

 the following characteristics : 



Antennae are but little longer than the head, flattened or 

 cylindrical, 10-jointed; the two basal joints differentiated, the 

 others closely united and never plumose. 



The eyes are round or reniform and holoptic in the male; 

 ocelli absent. 



Proboscis is not elongated, possessing small horny labella 

 and four-jointed palps. The first joint of the palp is short, 

 the two following of equal length, and the last one longer and 

 more slender than the preceding. 



The thorax is arched, without a suture, and the scutellum 

 small. 



The abdomen is cylindrical, made up of 7 or 8 (or more) 

 segments, and the genitalia are concealed. 



The legs are strong and not elongate, the femora broad and 

 flat, tibia usually with terminal spurs ; first joint of tarsi 

 longer than the following and usually dilated in the male, the 

 last joint small ; wings large and broad, with distinct alute, 

 anterior veins thickened, the others slender, auxiliary vein 

 terminating in the costa about the middle of the wing which 

 is not continuous beyond the tip of the wing. (See Fig. 1. 

 Plate XLIII.) Second longitudinal vein wanting, the first and 

 third lying close to each other, the third arising from the first 

 rectangularly before the end of the auxiliary vein; anterior 

 cross vein very short, fourth vein curved, forked nearly oppo- 

 site the anterior cross vein, the forks terminating near the 

 tip of the wing. (See Fig. 1, Plate XLIII.) 



Similiiim vittatum — Zetterstedt.* 

 [Trihiilatiim Lugger, Decoraiii (Walk), argas (Will). 



Adult — Female. Gray, nearly bare; dorsum of thorax 

 with five black stripes, the median one entire, the intermediate 

 pairs interrupted, the exterior pair spotlike. Each segment 

 of the abdomen with a black dorsal stripe, and basally on each 

 side with a black spot, the penultimate segment black. 



Wings whitish hyaline; halteres white; legs fuscous black; 

 the front side of the anterior tibite, the base of the middle and 

 hind tibiae, and the base of the middle and hind metatarsi 

 white; length 3 mm. (Zetterstedt.) 



* .Tohannsen. 



2-Univ. Sci. Bull.. Vol. VIU. No. 10. 



