INTRODUCTION. ^1 



The AcuLEATA have been divided into Series or Tribes. All 

 divisions, however, more comprehensive than families must be 

 considered moi*e or less conventional. 



Key to the Tribes of the Aculeata. 



A. Apical abdominal segments highly retractile ; 



abdomen with only three, four, or live visible 

 segments ; wings when at rest without a 

 longitudinal fold TUBULIFERA. 



B. Apical abdominal segments not so retractile ; 



abdomen generally with six ( 5 ) or seven ( S ) 

 visible segments ; wings when at rest with 

 or without a longitudinal fold. 



a. Hairs not plumose or branched ; basal joint 



of posterior tarsi not dilated. 

 a'. Wings when at rest without a longitu- 

 dinal fold. 

 a'. Petiole of abdomen with one or more 



scales or nodes : species social HETEROGYNA. 



b'. Petiole of abdomen simple : species 



solitary FOSSORES. 



b'. Wings when at rest with a longitudinal 



fold DIPLOPTERA. 



b. Hairs of the thorax plumose or branched ; 



basal joint of posterior tarsi more or less 



dUated ANTHOPHILA. 



The present volume takes in only the Fossores, Diploptera, and 

 Anthophila. 



Key to the Families of the Fossores. 



A. Posterior lateral angles of pronotum produced 



back to the base of the wings. 



a. A deep constriction between 1st and 2nd 



ventral segments of abdomen. 

 a'. Intermediate coxae contiguous : $ apterous. Mutillidae. 

 b'. Intermediate coxae widely separated : 5 



winged Scoliidae. 



b. No constriction between 1st and 2nd ventral 



segments of abdomen. 

 a'. Posterior legs short, not reaching much 

 beyond apex of abdomen. 

 «-. Eyes emarginate on inner side : $ 



winged *Sapygid<s. 



b-. Eyes not emarginate on inner side : $ 



apterous Thynnidae. 



b'. Posterior legs long, reaching well beyond 

 apex of abdomen ; eyes not emarginate on 

 inner side Pompilidae. 



B. Posterior lateral angles of pronotum not pro- 



duced back to base of the wings; pro- 

 notum often forming a mere collar Sphegidae. 



Not known to occur in India. 



