12G NORTH AMERICAN DIPTERA. 



f/lc^ TABLE OF GENERA. 



1. yC humeral bristle present. .... Helomyza Fallen. 

 %f{ N^ humeral bristle present. ........ 2 



2. No bristle above the base of the front coxae. . . Allophyla Loew. 

 A bristle above the front cox<e present . 3 



3. Spurs of the middle tibiae curved ; hair of the body comparatively long 



and soft. ....... Scoliocentra Loew. 



Spurs of the middle tibiae straight ; hair neither long nor soft. . 4 



4. Anterior oral border obliterated. . . . Anorostoma Loew. 

 Anterior oral border distinctly developed. ..... 5 



5. Eyes remarkably small. ' Gj^cothea Loew. 



Eyes not remarkably small. ........ 6 



6. Four bristles in the median dorsal thoracic rows. .... 7 

 But three bristles in the median dorsal rows. . Tephrochlamys Loew. 



7. Costal border of the wing very noticeably bristly ; front broad. 



Leria R. Desvoidy.- 

 Costal border with extremely small bristles; front narrow. 



Heteromyza Fallen. 



48. HETERONEURID./E. 



Head large, hemispherical. Face short, nearly perpendic- 

 ular. Vibrissal bristles present. Front broad, bristly to the 

 root of the antennae. Antennae porrect, short. Abdomen 

 elongate, narrow, somewhat compressed ; genitalia but little 

 prominent. Wings broad and rather long; all three basal 

 cells distinct; cross-veins much approximated. Legs long; 

 tibiae with or without a preapical bristle. 



Larvae of this family have been fol^nd in decaying wood, 

 under bark of trees, etc. They are slender, cylindrical, slight- 

 ly thickened posteriorly, white in color. The mouth booklets 

 are very small, the body segments not distinctly separated ; 

 abdominal segments with a transverse swelling for locomotion. 

 The larva? have the power of leaping, as do those of 

 PiophUd. The act is performed by fixing the month booklets 

 in the two chitinous, straight or curved booklets on the upper 



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