377 



per pair of thorns on apical segment directed upward 



Erax maculatus (p. 387) . 



— The pair of thorns at base of middle leg rather long and slender; 



postspiracular area of first abdominal segment with 3 spines ; 

 upper pair of thorns on apical segment directed upward and 



backward, their apices slightly curved downward 



Erax aestuans (p. 388) . 



10. Abdominal spiracles only moderately elevated; lateral cephalic 



process without a distinct protuberance on under surface at base 

 of lower thorn ; upper thorn on apical abdominal segment short, 

 directed upward 11 



— Abdominal spiracles much elevated; lateral cephalic process with 



distinct protuberance on under side at base of lower thorn ; up- 

 per thorn on apical abdominal segment long, directed backward 

 and slightly upward, its apex deflected downward 12 



11. The pair of thorns at base of middle leg- sheath, in front of wing, 



obtuse at apices Proctacantlvus philadelpJiicus (p. 385). 



— The pair of thorns at base of middle leg-sheath, in front of wing, 



acute at apices Proctacantlius milberti (p. 385). 



12. The pair of thorns at base of middle leg very short, the larger, pos- 



terior one not half as long as lower thorn of lateral cephalic 

 process ; seventh ventral abdominal segment with about 14 very 

 long spines in a transverse series which is widely interrupted at 

 center Asilus notatus (p. 385). 



— The pair of thorns at base of middle leg long, the larger, posterior 



one as long as lower thorn of lateral cephalic process ; seventh 

 ventral abdominal segment with about 24 moderately long spines, 



the series not noticeably interrupted at center 



Asilus sericeus (p. 386) . 



With the exception of those species whose descriptions follow, the 

 species in the keys were described in my paper which appeared in 

 191 5*, to which students are referred for descriptions and other de- 

 tails. 



Leptogaster fxavipes Loew 



Leptogaster flavipes Loew, Berl. Ent. Zeitschr., 1862, p. 193. 



Larva. — Length, 9 mm. White, semitransparent, glossy ; head 

 parts dark brown. 



Head viewed from above (dissected) as in Figure 7, Plate LITI, 

 maxillae with slight downward direction and appreciable curve, 

 maxillary palpi stout, at least twice as long as their diameter; (man- 

 dibles and labrum not distinguishable in specimen) ; dorso-central 



*Bull. 111. State Lab. Nat. Hist., Vol. 11, Art. IV. 



