388 bulletin: museum of comparative zoology. 



Sides of head of worker usually converging anteriorly, posterior 

 border of head of worker and female straight or convex or at 

 most very feebly excised. Basal border of mandibles without 

 vestiges of teeth 4 



4. Body of worker robust. Head of largest individuals not or 



scarcely longer than broad. Funicular joints 2-3 longer and 

 more slender than joints 6-8. Petiole usually with rather sharp 

 border. Body opaque, color of species light or dark red with 



brown or black gaster 5 



Body of worker more slender. Head of largest individuals usu- 

 ally distinctly longer than broad. Funicular joints 2-3 only 

 slightly more slender than joints 6-8. Petiole usually narrow, 

 rather thick and with blunt border. Color and sculpture 

 diverse 6 



5. Female larger than the largest workers, measuring 6-11 mm. 



. rufa group. 



Females not larger and sometimes even smaller than the large 



workers, measuring only 4-6 mm microgyua group. 



6. Thorax of worker rather short. Median joints of funiculi usually 



less than 1| times as long as broad; scapes stout, distinctly 

 curved at the base. Petiole flattened behind. Stipes of male 

 genitalia but slightly longer than the volsellae and sagittae. 



fusca group. 



Thorax of worker longer. Median joints of funiculi more than 



1^ times as long as broad; scapes slender, scarcely curved at the 



base. Petiole convex behind. Stipes of male genitalia much 



longer than the volsellae and sagittae. 



Subgenus Neoformica, subgen. nov. 



Subgenus Formica. 



Sanguinea group. 



Workers. 



1 . Palaearctic forms 2 



Nearctic forms 6 



2. Head and thorax rich red or Ijrownish red, head above more or 



less infuscated 3 



Head and thorax more yellowish red, head above not infuscated . 5 



