THE CANADIAN ENTOMOLOGIST. 221 



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Family XVII. — Pemphredonidse. 



The difference in venation of the hind wings and the distinctly petio- 

 late abdomen, as well as the venation of the front wings, readily 

 distinguish this family from the Crabronidce. In the former family the 

 median cell is fully twice as long as the submedian, while in the Pemphre- 

 donidce it is not twice as long as the submedian cell. 



Two subfamilies have been recognized, distinguished as follows : 



Table of Subfamilies. 



Antennae inserted close to the base of the clypeus ; front wings with 

 two cubital cells, rarely with one only . .Subfamily I., Pemphredonina^. 



Antennae inserted far above the clypeus on or near the middle of the 

 face; front wings with three cubital cells. . .Subfamily II., Pseninse. 



Subfamily I. — -Pemphredoniuce. 



The insertion of the antennas far forward, close to the base of the 

 clypeus, is the only reliable character to separate the subfamily from 

 the Pseninte, although, as a rule, the head is larger, more quadrate, 

 and the venation of the front wings is also different. 

 The genera may be recognized by the use of the following table : 



Table of Genera. 



Front wings with two recurrent nervures 4. 



Front wings with only one recurrent nervure. 



Front wings with two cubital cells 2, 



Front wings with only one cubital cell. 



Marginal cell short, triangular ; clypeus triangularly pointed 

 anteriorly or with a slight median production ; mandibles biden- 

 tate, the lower tooth the longer Ammoplanus, Girard. 



2. Petiole of abdomen long 3. 



Petiole of abdomen short. 



Second cubital cell quadrate ; recurrent nervure interstitial with the 

 first transverse cubitus or nearly ; mandibles biden- 

 tate Spilomena, Shuckard. 



3. Recurrent nervure received by the first cubital cell near its middle or 



little beyond ; second cubital cell quadrate ; ventral plate in ^ 



normal ; mandibles bidentate Stigmus, Jurine. 



Recurrent nervure received by the second cubital cell at its lower 

 basal angle or interstitial with the first transverse cubitus ; 



