wheeler: ants of the genus formica. 463 



surface of head without hairs. Pubescence on head and thorax dilute 

 and very short, completely lacking on the mesonotum. Head broad 

 behind and with a straight margin and rounded posterior corners. 

 Clypeus broadly rounded, scarcely carinate, shining, feebly and ob- 

 liquely striated. Mandibles shining, strongly sculptured; petiole 

 cuneate, squarely truncated above. 



Host (Temporary). Probably F.fusca var. subsericea. 



Type locality. — South Dakota: Hill City (Th. Pergande). 



British Columbia: Golden (W. Wenman). 



Nova Scotia: Digby (J. Russell). 



I have redescribed the worker of this species from a cotype. It is 

 easily recognized by the shape of the head and especially by the 

 petiole, M' hich differs from that of all other species of Formica known to 

 me. The palpi, too, as Emery has observed, are remarkably short. 

 The specimens from the three localities mentioned above all agree in 

 having extremely few or no hairs on the dorsal surface of the body 

 and none on the gula, thus coinciding with Emery's remark " superne 

 haud pilosa," so that the following form, which I first described as a 

 distinct species and later regarded as identical with the typical dako- 

 tensis, may be retained as a variety. 



51. F. dakotensis var. montigena Wheeler. 



F. montigena Wheeler, Bull. Amer. mus. nat. hist., 1904, 20, p. 374, ^ 9 cf. 



Worker. Length 3.5-6.5 mm. 



Dift'ering from the worker of the typical dakotensis in ha\'ing longer 

 and more numerous erect hairs on the upper surface of the head, 

 thorax, and petiole, and in having a few erect hairs on the gula. The 

 pubescence on the gaster and legs seems also to be a little longer and 

 more distinct. The gaster is more brownish or reddish and the base 

 of the first segment is often yellow or red. 



Female. Length 7 mm. 



Mandibles and clypeus like those of the worker. Head large, as 

 broad as long, its sides straight, slightly converging in front, its pos- 

 terior angles rounded, its posterior border feebly excised. Thorax 

 distinctly narrower than the head. Petiole extremely thick and blunt, 

 its upper border transverse and feebly excised when seen from behind. 

 Wings as long as the body (7 mm.). 



Body and legs very glabrous and shining. Mandibles coarsely 

 striatopunctate. Clypeus delicately striated anteriorly. Antennae 

 subopaque. 



Hairs suberect, sparse, yellowish, longest on the gaster, especially 



