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 



261) 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 APIXA 

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



tongued bees. (Page 267) AXDREXIDAE 



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

 (Page 267) APIDAE 



KEY TO THE MORE IMPORTANT FAMILIES OF DIPTERA 1 



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 PSVCHODIDAE 



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. 



