THE COMPOUND NESTS. 



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and not a few were seen in the middle of foot-paths, although they 

 prefer loose soil. In several parts of a ten-acre field where the soil is 

 of the usual character, I found nests of this Myrmica containing the 

 symbiotic species. Three of these compound colonies were present, 

 two now being in a collection stored at my home in Utah, the other 

 being the one you have examined. I never succeeded in finding one 

 of the compound nests elsewhere than in this particular field. My 



FIG. 260. Symmyrmica chamberlini. (Original.) a and b, worker; c, mandible, 

 d, hairs of same ; e and /, ergatomorphic male ; g, mandible of same. 



attention was drawn to the first compound nest by seeing two indi- 

 viduals of Symmyrmica disappear into a burrow immediately following 

 a Myrmica worker. Upon excavating I found others of the symbiotic 

 form, mostly collected in a chamber about eight inches below the sur- 

 face of the ground. The nest seemed to be above the average in size." 

 Myrmica mutica, which closely resembles in structure and habits the 

 European M. rubida, is very common in the mountains of Colorado, 

 but although I examined many nests in that state during two different 

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