22 



CONNECTICUT GEOL. AND NAT. HIST. SURVEY. 



[Bull. 



HYMENOPTERA. 



Key to Sup erf amities. 



A deep constriction at the base of the first abdominal seg- 

 ment,* conspicuously separating the abdomen from the 

 thorax 



No marked constriction at the base of the abdomen, the 

 thorax and anterior abdominal segments being approxi- 

 mately equal in breadth TENTHREDINOIDEA p. 



First abdominal segment *(sometimes also the second) form- 

 ing a lens-shaped scale or knot (petiole), strongly differen- 

 tiated from the remaining abdominal segments (gaster) 



FORMICOIDEA p. 



25 



577 



*In all the Hymenoptera the segment which is morphologically the first abdominal seg- 

 ment (propodeum) is intimately fused with the thorax, of which it seems to be a part. In 

 this work the general usage of descriptive writers is followed, and the segment which is 

 apparently the first abdominal segment, though morphologically the second, is uniformly 

 called the first abdominal segment. 



