22 DIPTERA OF NORTH AMERICA. 



Macq., COLAX Wied., TRICHOPSIDEA Westio., and SYMMICTUS Loew, 

 all of which are characterized by their very short proboscis. To 

 the second belong the genera: FALLENIA Meig. , NEMESTRINA Wied., 

 MEGISTORHYNCHUS Macq., TRICHOPHTHALMA Westw., and RHYN- 

 CHOCEPHALUS Fisch. 



We are only acquainted with a single N. A. species belonging 

 to HIRMONEURA Meig. 



FAM. XVIII. MID A SID AE. 



Charact. Three basal cells much prolonged ; third longitudinal vein fur- 

 cate ; posterior intercalary vein always present, whereas the ante- 

 rior one is often wanting ; veins of the wings varying ; wings naked. 

 Antennfe clavate with the third joint consisting of several distinct 

 segments. Under lip fleshy. Empodiiim very little developed. 



To this family belong the genera: MIDAS Fair., CEPHALOCERA 

 Latr., RHOPALIA Macq., and DOLICHOGASTER Macq. POMACERA 

 Macq. may also be placed here till its true place is found. 



The N. A. species hitherto known belong only to the genus 

 MIDAS Fabr. 



FAM. XIX. ASILIDAE. 



Charact. Three basal cells much prolonged. Third longitudinal vein of 

 the wings furcate, the two intercalary veins always present. Third 

 joint of the antennae simple; under lip forming a horny sheath; 

 empodium similar to a horny bristle. 



This family, rich in species of the most varied forms, is divided 

 into three sections. The first of them is that of the DASYPOGO- 

 NINA, differing from the two others by its second longitudinal vein 

 running into the border of the wing, whereas in the others it 

 unites with the first longitudinal vein before the border of the wing. 

 The considerable number of genera requires a further division into 

 two subordinate groups, the first of which comprises those genera 

 in which the anterior tibiae end in a hooked spine, whereas the 

 genera of the second portion have no such spine. Consequently 

 the genera belonging to the first group of Dasypogonina are as 

 follows: DASYPOGON Meig., SAROPOGON Loew, LASTAURUS Loew, 

 MORIMNA Walk. , C YRTOPHRYS Loew, LAPARUS Loew, BRACHYRHO- 

 PALA Macq., CHEILOPOGON Bond., LAGODIAS Loew, and PEGE- 



