434 bulletin: museum of comparative zoology. 



The specimens from Boulder, Colorado, represent a series from a single 

 colony, the largest with a few suberect hairs on the tibiae, the medium 

 sized and small workers without any, so that one is in doubt as to which 

 subspecies they belong. I have not seen females and males of the 

 true obscuripes and am inclined to believe that further study may show 

 that both obscuripes and aggcrans are really the same rather variable 

 subspecies. Both build the same type of nest, a dome-shaped mound 

 of twigs and other vegetable debris, often very coarse and very much 

 like the nests of the European pratensis in size and shape. Formica 

 obscuripes, like the typical aggcrans, is peculiar to British Columbia and 

 the Northwestern States, being best represented at altitudes between 

 5,000 to 8,000 ft. 



30. F. RUFA obscuripes var. whymperi Forel. 



F. rufa St. obscuripes var. whymperi Forel, Ann. Soc. ent. Belg., 1904, 48, p. 



152, ^ . 

 F. rufa obscuripes var. whymperi, Wheeler, Ants, 1910, p. 570. 



Worker. With the color and aspect of the darker forms of F. 

 pratensis of Europe; front, vertex, occiput, and dorsum of pronotum 

 and mesonotum blackish; with the same pubescence and sculpture, 

 but with the sparse pilosity of obscuripes; tibiae without suberect 

 hairs. 



Type locality. — British Columbia : Vermillion Pass, 5,000-6,500 

 ft. (E. Whymper). 



This form seems to have been described from a single worker. 

 I have not been able to recognize it among the material collected in 

 British Columbia by J. C. Bradley and W. Wenman. 



31. F. truncicola truncicola Nylander. 



F. truncicola Nylander, Acta Soc. Fennica, 1846, 2, p. 907, S 9 ; Ibid., 1849, 

 3, p. 26, 29, c?; Forster, Hymen, stud., 1850, 1, p. 21, 9 cf (nee g ); 

 Schenck, Jahrb. Ver. nat. Nassau, 1852,8, p. 33, 139, 145, ^ 9 &] 

 Stettin, ent. zeit., 1853, 14, p. 160; Mayr, Verb. Zool. bot. ver. Wien, 1855, 

 5, p. 334, y 9 cf; Europ. Formicid., 1861, p. 46, 48, ^ 9 cf ; Forel, 

 Bull. Soc. Vaud. sci. nat., 1875, ser. 2, 14, p. 58; Mayr, Fedtschenko's 

 Turkestan. Formicid., 1877, p. 6; Ern. Andre, Spec. Hymen. Europe, 

 1882, 2, pt. 14, p. 183, 187, 189, ^ 9 cf; Dalla Torre, Catalog. 

 Hymen., 1893, 7, p. 213; Bingham, Fauna Brit. Ind., 1903, 2, p. 334; 

 Forel, Ann. Mus. St. Petersbourg, 1904, 8, p. 385; Ruzsky, Formicar. 

 Imper. Ross., 1905, p. 330, fig. 63, 64. 



