OF rniiiADELpniA. 49 



dusky ; antcnnoc twice the length of the head and thorax, second 

 joint very small, third joint as long as as the fourth and fiftli 

 taken together, the remaining joints a little dusky, dilated at their 

 bases, and somewhat excavated in their middles ; wings immac- 

 ulate ; nervures, stigma and interstice of the first and second ner- 

 vures, dull-yellowish ; feet pale-brownish ; abdomen somewhat 

 darker than the thorax, with three series of black dots, one lateral, 

 and one ventral ; pleura and pectus whitish yellow. [25] 



Length half an inch. 



The antenna) by their length, the second and third joints, and 

 the form of those of the flagellum, show an alliance with the genus 

 Nephrotoma, but as they have but thirteen joints, the insect must 

 be regarded as a Tipida. 



4. T. COLLARIS. — Thorax blued-black, lineate with yellow j 

 tergum yellow with blackish bands. 



Inhabits Pennsylvania. 



Head fulvous; antennae, first and second joints, rather paler 

 than the head; palpi fuscous, pale at base; occiput black: tho- 

 rax blued-black, the collar, two lines each side confluent before 

 and behind, scutel and metathorax, bright yellow, the latter with 

 two confluent blued-black spots at tip ; poisers brown, tip of the 

 capitulum yellowish ; wings with a brown stigma, nervures 

 brown, differing in arrangement from those of the preceding 

 species and from those figured by Meigen : feet brown, basal portion 

 of the thighs pale ; tergum yellow, segments black-brown on their 

 posterior half ; venter pale-yellow, segments dusky on their pos- 

 terior half with a silvery reflection. 



Length a little less than half an inch. 



5. T. ANNULATA. — A dark brown stigma ; abdomen pale, an- 

 nulate with l>lack. 



Inhabits Pennsylvania. 



Antennae fuscous, first andsecond joints whitish; rostrum, and 

 lower portion of the front whitish ; vertex and' occiput dusky ; 

 palpi fuscous; thorax yellowish-brown, [26] the indented lines 

 paler; metathorax light livid; wings with a brown stigmata, 

 nervures brown, arranged like those of Meigen's fig. 9, pi. G ; feet 

 dusky-brownish ; abdomen yellowish-white, incisures and their 

 margins black, forming annulations complete. 

 1823.] 3 



