22 ENTOMOLOGICAL NEWS. [Jan., 'iS 



P. crassicornis Emery. 



This species has workers that are distinctly more rufous 

 colored than are those of any other species of this genus, the 

 abdomen is very dark. The writer has found nests of this 

 ant under pavement walks and around the roots of trees. 



P. tysoni Forel. 



Workers of this shining yellow species have been taken only 

 once. The workers are easily identified from the other work- 

 ers of this genus by their yellow color and smooth shining ap- 

 pearance. 



P. dentata Mayr. 



The workers are easily confused with those of P. vinelan- 

 dica, from which they differ in the sculpture of the head and 

 in their larger size. The nests are small crater-shaped af- 

 fairs ; sometimes they nest under stones or logs. The work- 

 ers store seed in their nests. 



P. vinelandica Forel. 



The workers of this species are often confused with those 

 of P. dentata, from which they differ in their smaller size, 

 less numerous hairs, and the sculpture of the head. They 

 build nests under stones or in the open. The field nests are 

 small crater-shaped mounds only a few inches in diameter. The 

 workers store small grass seeds in their nests. 



Genus Tetramorium Mayr. Subgenus Tetramorium s. str. 

 T. caespitum L. 



This species has been introduced into America from Europe 

 and occurs principally in our large cities. The workers have 

 a striated thorax and head. From their habit of nesting be- 

 neath pavement walks they are commonly known as the "pave- 

 ment ant." 



Subfamily DOLICHODERINAE. 



1. Chitinous integument hard and brittle; epinotum with declivity 



strongly concave; principally arboreal in habits. 



Dolichoderus, subgenus Hypoclinea 

 Chitinous integument thin and flexible 2. 



2. Epinotum with a conical elevation; terrestrial species building 



dome-shaped mounds in sunny spots Dorymyrmex 



Epinotum not as above 3 



