326 



— Dorsal abdominal segments without long slender curled hairs, the 



transverse series consisting of strongly chitinized thorns which 

 alternate in size 8 



3. The short stout thorns on abdominal segments 2 to 4 bent upward 



at right angles at bases and apices ; armature of head consisting of 

 a lunate series of 4 strong thorns on upper margin the bases of 

 which are contiguous, and 2 shorter, downwardly directed thorns 

 on middle near lower margin Spogostylum anale (p. 328). 



— The short stout thorns on abdominal segments either bent up at 



apices only and the armature of head not as above, or if the short 

 thorns are bent up both at bases and apices the head armature con- 

 sists of 8 thorns 4 



4. Upper pair of cephalic thorns slender, widely separated at base ... 5 



— Upper pair of cephalic thorns very stout, contiguous at base 



{Antlirax) 7 



5. The short abdominal thorns bent upward at right angles at bases 



and apices Exoprosopa fasciataf (p. 329) . 



— ■ The short abdominal thorns not bent up at base, only so at apices 

 6 



6. Lateral pair of cephalic thorns contiguous at base, the lower one 



without basal protuberance or hairs 



Exoprosopa fascipennis (p. 330) . 



— ■ Lateral pair of cephalic thorns rather widely separated at base, the 

 lower one with a short wartlike protuberance at base on under side 

 which has upon it 2 or 3 hairs Sparnopolius fulvus (p. 331). 



7. Upper pair of cephalic thorns simple, without a small tooth at base 



on outer side; viewed laterally the middle one of the 3 caudal 

 thorns on each side is much smaller than the lower one, sometimes 

 indistinguishable Anthrax liypomelas (p. 334). 



— Ul)per pair of cephalic thorns each with a small tooth on outer side 



at base; viewed laterally the middle one of the 3 caudal thorns on 



each side is about as large as the lower one 



Antlirax lateralis (p. 332) . 



8. Upper pair of cephalic thorns directed outward and slightly up- 



ward ; apices of wing sheaths extending beyond apices of sheaths 

 of middle legs My das davatus (p. 336) . 



— LTpper pair of cephalic thorns directed forward and slightly down- 



ward ; apices of wing sheaths not extending beyond apices of 

 sheaths of middle legs {Asilida) 9 



9. Prothoracic spiracle merely a rugose area, without well-defined reni- 



form portion ; abdominal spiracles very large 



Promaclius vertehratus (p. 337) . 



— Prothoracic spiracles rugose, but with a well-defined reniform area 



which is distinctly elevated 10 



10. Apices of sheaths of fore legs extending very distinctly caudad of 

 apices of wing sheaths Deromyia wintliemi (p. 338). 



