SYNOPSIS OF NORTH AMERICAN SYRPHID^. 135 



I think that this character is of but little value to distinguish our spe- 

 cies. The other character used for this genus is of less value still: I 

 mean the excision of the third joint of the antennae above, as such ex- 

 cision in a less degree is found in most of the Volucellie. Mr. Bigot has 

 established the genus Atemnocera on the presence of bristles on the 

 scutellum alone, the third joint of the antennae not being excised above. 

 If the small difference that is thus left as the sole character for Temno- 

 cera were made a criterion by which to base other genera in this family, 

 how many would there be? 



TABLE OF SPECIES. 



1. — Thorax and abdomeu very thickly furry, more or lesa yellowish, pilose. Face 

 much excavated below the autennic ; arista very long and densely plumose : 

 second segment of the abdomen yeUow on the sides; wings with a dark 



brown spot; large species 2 



Thorax and abdomen not thickly pilose 3 



2.— Face black or chestnut ; yellow pilose ; dorsum of thorax and pleurte wholly yel- 

 low pilose evecta 



Face yellow ; thickly yellow pilose ; cheeks black ; dorsum of thorax and pleura- 

 black pilose facialis 



3. — Deep black, green, violet, or copi^ery colored species ; cheeks not light colored . 4 

 Prevailing color light ; cheeks yellowish, wholly so or with a black stripe . 9 

 4. — Base of wings yellow ; face light yellow, with yellow pile; sides of thorax and 

 the scutellum reddish or yellowish ; basal two-thirds of tibiaj reddish yel- 

 low , vesiculosa, eugenia. 



.Base of wiugs not yellow but hj aline or brown 5 



5. — Wiugs hyaline, except a spot at end of auxiliary vein and on the crosa-veins : 



body wholly deep colored except, sometimes, the head 6 



Wings more or less dark brown on the basal part in front 8 



6.— Face much produced downward into an acute cone ; third joint of autennte elon- 

 gate as usual 7 



Face obtuse below, not produced downward, in the middle with an obtuse tuber- 

 cle ; third joint of antenuce very short, triangular obesa 



7.-^Face and front wholly black Comstocki 



Face and front, except the cheeks, deep reddish-yellow victoria 



g._\Vings broadly deep brown at the base, ending abruptly near the tip of auxiliary, 



and thence yellowish along the costa; abdomen clothed chiefly with short 



erect hairs ; face considerably excavated below the antennse . taexicana 



Wings brown in the costal and subcostal cells ; face more or less red, lightly 



excavated below the antennae anna 



9._Third joint of antennse deeply excised above; face produced forwards below 



Hagii 

 Third joint of antenme not, or but little, excised above; face produced down- 

 ward, as usual 10 



10.— Large species (11™"'+) . . .• 11 



Smaller species 13 



11. — Face and cheeks wholly yellow megacephala 



Face and cheeks not wholly yellow 12 



12.— Cheeks black, shining ; black of the abdominal segments prolonged in the mid- 

 dle anteriorly (11-12™^) avida 



Cheeks yellow with a rather narrow brown or black stripe ; black of the abdomi- 

 nal segments less distinct in the middle isabeUina 



