FIELD BOOK OF INSECTS. 



9. Pupae naked; abdominal pedicel consisting of two 

 segments 10. 



Pupae enclosed in cocoons; pedicel with one segment; 

 gaster with a distinct constriction between its first and 

 second segments; frontal ridges separated or, if close 

 together, dilated to form oblique or horizontal plates 

 partly covering insertions of antennae. Ponerinae, of 

 which Ponera coarctata is our common species. It nests 

 under stones and in rotten logs in open woods and along 

 hedges. 



10. Frontal ridges very close together, almost vertical, 

 not at all covering antennal insertions; eyes always 

 very small or absent; tropical or subtropical. Dorylinas. 



Frontal ridges of a different conformation and cover- 

 ing antennal insertions; eyes rarely vestigial or absent. 

 Myrmicinae. In the following, workers are developed and 

 clypeus usually extends back between frontal ridges . . . . 1 1. 



11. Postpetiole joined to upper surface of gaster, which is 

 flattened above, more convex below, and pointed at tip. 



Cremastogaster. 



Postpetiole joined to front end of gaster, which 

 is of the usual shape; antennal club consisting of several 

 joints, or antennas not 1 1 -jointed 12. 



12. Antennae lo-jointed, with a 2-jointed club . . Solenopsis. 

 Antennal club, when developed, with more than 



two joints 13. 



13. Posterior margin of clypeus elevated in the form of a 

 welt, bordering antennal depression in front; antennas 

 of workers with n (sub-genus Xiphomyrmex) or 12 joints, 

 of male lo-jointed Tetramorium. 



Posterior border of clypeus not thus elevated 14. 



14. Antennae 1 1 -jointed 15. 



Antennae 12-jointed 16. 



15. Thorax and petiole without any traces of teeth or 

 spines; pronotum never angular; petiole distinctly pedun- 

 culate Monomorium. 



Epinotum (posterior part of thorax, above) armed 

 with spines or teeth. Leptothorax (see 19) ; Symmyrmica, 

 which fits here, may also be found. 



16. Workers strongly dimorphic, usually without inter- 



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