202 



15. Pogonomyrmex barba tus Smidi, var. typicus and 

 molifaciens Buck. 



The nests of thèse ants are seen in ail their beauty between Aguas 

 Calientts and the City of Mexico. South of Lhe Ciudad th^y extend up 

 onto the slopes of Ajusco to an altitude of between 8,000 and 

 9,000 feet, but they were not seen near the summit nor on the sou- 

 thern slopes as far as Cuernavaca. They were observed most carefuUy 

 at Aguas Calientes where both varieties may often be fouiid in 

 neighboring nests. One mixed nest was found containing about equal 

 numbers of workers of both the typical and the molifaciens variety. 



16. Pheidole tolteca Forel. 



Cuernavacaj Dec. 26. A few workers taken on the flowers in the 

 Borda Garden. 



17. Pheidole carbonaria Perg., var. calens Forel. 



Aguas Calientes, Dec. 31. This feeble Pheidole was found in a 

 number of instances inhabiting small nests within the precincts of the 

 Pogonomyrmex colonies, either on the denuded disks or on the 

 slopes of the gravel cônes near the entrances of the agriculturals. It 

 was seen more frequently in ihis association than either Dorymyr- 

 meœ pyrcunicus or Forelius Maccooki, and was not seen nesting 

 by itself as is very frequently the^case with thèse species. 



18. Pheidole optiva Forel. 



Cuernavaca, Dec. 26. Under stones in the shade of some trees at 

 the bottom of one of the barrancas. Formicaries large. Ants, both 

 soldiers and workers remarkably slow in their movements. 



19. Pheidole laevivertex Forel. 



In the same localities as P. optiva, which this species resembles 

 very closely to the naked eye. 



20. Pheidole Hyatti Emery. 



Cuernavaca, Dec. 30. Common under stones on the nioist, grassy 

 hill-slopes used as pasture lands. 



21. Pheidole Vasliti Perg., var. hirtula Forel. 



Querelaro, Dec. 30. Common under stones on the dry hill-slopes 

 about the town, usually in the vicinity of the nests of Pogonomyr- 

 mex. It is in ail probability a carnivorous species as ail the nests exa- 

 mined contained a number of dead agriculturals. Thèse it probably 

 coUects from the refuse heaps of its large and powerful neighbors. 

 P. Vasliti belongs to a neotropical subdivision of the genus with 

 polymorphic soldiers (like P. Kingii André var. instabilis Emery of 

 Texas). Ail the nests contained a considérable number of soldiers 



