226 ERNEST A. BACK. 



hair; occiput more or less densely clothed with hair and 

 bristles above, below with a dense beard. Proboscis very 

 small, slender. Thorax only moderately well arched, usually 

 clothed on dorsum with fine erect pile and, on the lateral 

 margin and posterior callosities, with fine, sometimes stouter, 

 bristles ; pleurae with long pile upon the mesoplurae and before 

 the halteres; scutellum wholly clothed with long erect pile, 

 only seldom long slender bristles on the posterior margin. 

 Abdomen broad, stout, compressed, all the segments on the 

 middle of the sides with more or less well developed short 

 bristles, and upon the posterior margins with pruinose cross- 

 bands, entire or interrupted. Genitalia of male small ; the 

 last two segments of the abdomen usually partially retracted. 

 Legs moderately stout with weak bristles, very numerous on 

 the tibiae and tarsi ; pul villi normal ; the anterior tibiae without 

 a terminal claw-like spur. First posterior cell of wing vari- 

 able, open, closed, or narrowed; remaining posterior cells wide 

 open; the anal cell closed and slightly petiolate; the anterior 

 branch of the third longitudinal vein forming a long letter S. 

 In uniting Laphystia and Laphysctis I am following Bigot 

 Dipteres nouv. on peu connus, XVII, Annales de la Soc. Ent. 

 de France, 1S77), and Dr. Fr. Hermann (Beitrag zur Kenntnis 

 der Asiliden, Berl. Ent. Zeit., L, 33, 1905). Bigot writes that 

 the reciprocal similarity between Laphystia and Laphyctis is 

 such that, in his opinion, it renders wholly irrational the sepa- 

 ration of the types which have served in their establishment. 

 Dr. Hermann says that the difference to be found in the width 

 and breadth of the head, wing venation, hairiness of the hind 

 tibiae and size of the genitalia are only relative, and not to be 

 relied upon for generic distinction. That this genus is inter- 

 mediate between the Dasypogoninse and the Laphrinae may 

 easily be seen by referring to Dr. Hermann's above-mentioned 

 paper, page 31. It will be noticed that the figures 15-18 of 

 the wing of Laphystia sabulicola show a marked variation in 

 the union of the first and second longitudinal vein. Dr Her- 

 mann places Asicyia a synonym of Laphystia as he finds that 

 intermediate stages are to be found between normal and ves- 

 tigal pulvilli, and open and closed first posterior cells even in 

 specimens of the species Laphystia. 



