APPENDIX B. 



KEY TO THE SUBFAMILIES, GENERA AND SUBGENERA OF THE 

 NORTH AMERICAN FORMICID/E, FOR THE IDENTI- 

 FICATION OF THE WORKERS. 



1. Cloacal orifice ventral, slit-shaped; sting well developed or vestigial; ab- 



dominal pedicel consisting of one or two segments 2. 



Cloacal orifice terminal, circular, surrounded by a fringe of hairs; abdominal 

 pedicel consisting of only a single segment ; no constriction between the 

 first and second gastric segments ; pupae usually enclosed in cocoons. 



Subfamily Camponotinae. 



2. Sting developed ; sometimes very small but nevertheless exsertile ; abdominal 



pedicel consisting of one or two segments; when of only one there is a 



distinct constriction between the first and second gastric segments 3 



Sting vestigial ; abdominal pedicel consisting of a single segment ; no con- 

 striction between the first and second gastric segments; anal glands which 

 produce a secretion with a peculiar rancid-butter odor ("Tapinoma odor") 

 are often present ; pupae naked Subfamily Dolichoderinae. 



3. Pupae always enclosed in cocoons; abdominal pedicel consisting of a single 



segment; gaster with a distinct constriction between its first and second 

 segments : frontal carina? separated or close together ; when close together 

 they are dilated to form oblique or horizontal laminae partly covering the 



insertions of the antennae Subfamily Ponerinae. 



Pupae naked ; abdominal pedicel consisting of two segments in the American 

 species (excepting Clieliomynnc.v of Central America) 4. 



4. Frontal carinae very close together, almost vertical, not at all covering the 



antennal insertions. Eyes always very small or absent ; tropical and sub- 

 tropical Subfamily Dorylinae. 



Frontal carinae of a different conformation and covering the antennal inser- 

 tions. Eyes rarely vestigial or absent; cosmopolitan. 



Subfamily Myrmicinae. 

 Subfamily PONERIN^. 



i. Frontal carinae closely approximated; antennae inserted very near the oral 



margin; tip of gaster strongly deflected downward 2. 



Frontal carinae of a different conformation; tip of gaster not deflected down- 

 ward 3. 



2. -Front of clypeus projecting in the middle; petiole nodiform. 



Sysphincta Roger. 

 Clypeus not projecting in the middle; petiole surmounted by a scale. 



Proceratium Roger. 



3. Mandibles linear, inserted close together at the middle of the oral border; 



petiole terminating in a point or spine above Odontoniachus Fabr. 



Mandibles inserted at the corners of the head ; petiole rounded or flattened 

 above 4. 



4. Antennae very thick and robust .' 5. 



Antennae not greatly thickened 6. 



5. Pygidium with a row 7 of prominent prickles on its lateral border; last antennal 



joint not greatly enlarged Acanthostichus Mayr. 



Pygidium without prominent prickles on its lateral border ; last antennal 

 joint greatly enlarged. .Ccrafachys F. Smith: subgen. Parasyscia Emery. 



557 



