286 



SYRPHID.E. 



that there is a kind of secondary heart, at the extremity next the 

 thorax, for the purpose of causing the reflux. This structure has 

 been observed in many of the genera allied to Sueva, and it is sup- 

 posed to be also widely diffused among the Muscidce." 

 The species may be grouped thus : 



a. Abdomen oblong-oval, with straight or arched yellow bands. Legs 

 simple. 



b. Wings with the fourth longitudinal vein curved in the disc. 

 c. Eyes bare. Species 1. 

 c c. Eyes hairy. Species 2. 



b b. Wings with the fourth longitudinal vein not or hardly curved. 

 d. Eyes bare. 



e. Scutellum pale. Head yellow. 

 /. Bands of the abdomen simple. 



g. Bands of the abdomen straight. Species 3-6. 

 (j (j. Bands of the abdomen arched. Species 7-9. 

 //. Bands of the abdomen double. Species 10. 

 e e. Scutellum reueous. Species 11. 

 d d. Eyes hairy. 



h. Bands of the abdomen straight. 



i. Intermediate bands of the abdomen entire. Species 



12, 13. 

 i i. All the bands of the abdomen interrupted. Species 



14-17. 



li li. Bands of the abdomen arched or hmulate. Species 18. 

 a a. Abdomen narrow, linear ; the yellow bands always straight. 

 #. Scutellum yellow. Epistoma white or yellow. 



I. Bands of the abdomen interrupted. Species 19, 20. 



I 1. Intermediate bands of the abdomen entire. Species 21, 22. 

 k k. Scutellum and epistoma asneous. 



m. Tarsi of the male dilated. Fore tarsi of the female short, 

 serrated. 



n. Abdomen with interrupted bands or quadrate spots. 

 o. Epistoma long, conical. Species 23. 

 o o. Epistoma tuberculate, not long nor conical. Species 



24-28. 



n n. Abdomen ferruginous-red. Species 29. 

 m m. Tarsi simple in both sexes. Species 30-33. 



1. alneti, Fin. syrph. 38. 4 (1816); Mg. ; Mq. ; Ztt. glautius, 

 Pz. ! fn. lix. 17. Nigra, scutello fulvo, alis subcinereis, abdomine 

 flavo-quinquefasciato, pedibus luteis, femoribus basi nigris, tibiis pos- 

 ticis piceo-cinctis. Long. 6 ; alar. 12 lin. 



Black, clothed with tawny hairs. Vertex bluish-black; epistoma 

 yellow, with a black scapula. Scutellum dull tawny. Wings slightly 

 grey, brownish at the base and along the costa ; stigma dark brown. 



