KEY TO GENERA OF ANTS. 



1. Cloacal orifice ventral, slit-shaped 7 



Cloacal orifice terminal, circular, surrounded by a 



fringe of hairs; abdominal pedicel consisting of only a 

 single segment; no consti Action between the first and 

 second gastric segments (The gaster is the swollen portion 

 of the abdomen); pupas usually enclosed in a cocoon. 

 Camponotinag 2. 



2. Antennae Q-jointed Bracliymyrmex. 



More than 9 antennal joints 3. 



3. Workers strongly polymorphic, i. e., some large- 

 headed, some small-headed, and some intermediate .... 



Camponotus. 



Workers not polymorphic though often of variable 

 size 4. 



4. Clypeal depression (The clypeus is the lower part of 

 the face; the labrum, or lip, is attached to it.) distinctly 

 separated from antennal depression Prenolepis. 



Clypeal depression confluent with antennal depres- 

 sion 5 



5. Second to fifth joints of funiculus (the antenna 

 beyond the first joint; the "lash") not longer than succeed- 

 ing joints; ocelli usually absent Lasius. 



These joints longer than the succeeding; ocelli distinct; 

 fourth joint of maxillary palpi a little longer than fifth. . . .6. 



6. Mandibles with broad, dentate, apical border. Formica. 

 Mandibles narrow, falcate, and pointed. .Polyergus. 



7. Sting developed, sometimes very small but still 

 exsertile; pedicel consisting of one or two segments (when 

 of only one, a distinct constriction between first and 

 second gastric segments) 9. 



Sting vestigial; pedicel with one segment; no con- 

 striction between first and second gastric segments; often 

 with a peculiar, rancid-butter odor; pupas naked. Doli- 

 choderinse 8. 



8. Chitinous integument hard and brittle, often strongly 

 sculptured; thorax and petiole often spinose or angular. 



Dolichoderus. 



Integument thin and flexible, smooth or very finely 

 sculptured; thorax and petiole unarmed; scale of petiole 

 vestigial or absent Tapinoma. 



21 417 



