CLASSIFICATION OF INSECTS 321 



G. First abdominal segment distinctly separated from 



the second on the ventral side by a constriction. 

 H. Tibia of second pair of legs with two terminal 

 spurs ; females wingless. Velvet ants. (Page 



26l) MUTILLIDAE 



HH. Tibia of second pair of legs with single terminal 

 spur . ........ . SCOLIIDAE 



GG. First and second segment of abdomen not separated 

 on ventral side by constriction. (Page 261) 



PSAMMOCHARIDAE 



FF. Prothorax forming a narrow collar, not reaching to base 



of wing. 

 G. Base of abdomen with a long, slender petiole. (Page 



262) SPHECIDAE 



GG. Base of abdomen without long, slender petiole. 



BEMBECIDAE 



DD. First segment of tarsus of hind-leg expanded and flattened, 

 furnished with numerous hairs, often poorly developed in para- 

 sitic bees. Bees. (Page 266) .... Superfamily APINA 

 E. Glossa short and flat, no longer than the mentum. Short- 



tongued bees. (Page 267) ANDRENIDAE 



EE. Glossa long and slender, not flattened. Long-tongued bees. 

 (Page 267) APIDAE 



KEY TO THE MORE IMPORTANT FAMILIES OF DIPTERAi 



A. Adults nonparasitic upon the warm-blooded vertebrates; habits variable. 



Abdomen distinctly segmented. Rarely viviparous. 



B. Anal cell rarely narrowed at the margin ; antennae consisting of more 

 than 5 joints, usually elongate, filiform, and verticellate, rarely pecti- 

 nate or with a differentiated style or arista . . . NEMATOCERA 

 C. Veins of the wings covered with hairs, the usual cross veins want- 

 ing. Small mothlike flies PSYCHODIDAE 



CC. Veins and margin of the wings fringed with scales. Mosquitoes. 



(Fig. 455) CULICIDAE 



D. Thorax with a distinct V-shaped suture ; wings variable. Crane- 

 flies. (Fig. 453) TIPULIDAE 



DD. Thorax without the distinct V-shaped suture. 



E. Discal cell present. False crane-flies . . . RHYPHIDAE 

 EE. Discal cell wanting. 



F. Wings with few longitudinal veins ; tibiae without spurs. 



Gall-gnats. (Fig. 458) CECIDOMYIIDAE 



FF. Tibiae with spurs ; coxae elongate. Fungus-gnats. 

 (Fig. 459) MYCETOPHILIDAE 



1 By C. W. Johnson, Curator Boston Society of Natural History, 



