MOUNTAIN ANTS OF NORTH AMERICA. 509 



node is much less compressed anteroposterior!;^', its posterior surface 

 being much more convex than in typical nevadensis. The color is 

 considerably darker, the body being castaneous, with the head and 

 gaster, except its incisures, blackish, the mandibles, clypeus, antennae 

 and legs yellowish brown, the femora infuscated in the middle. Pilos- 

 ity as in the t^'pical form. 



Female (dealated). Length: 3.5 mm. 



Smaller than the female of typical nevadensis, with longer and more 

 slender epinotal spines and the funicular joints 2-8 shorter. Sculp- 

 ture of the head, thorax and petiole a little coarser. Petiolarnode like 

 that of the worker. In the typical form it is much compressed antero- 

 posteriorly and has a sharp, transverse superior border. There is 

 very little difference in color between the two forms. 



Described from numerous workers and a single female taken from 

 small colonies nesting under the edges of stones in Tenaya Canyon, 

 Yosemite Valley, Cala. Seven workers from Angora Peak, 8600 ft., 

 near Lake Tahoe, Cala., though differing in certain details of sculp- 

 ture are nevertheless referable to this subspecies. 



39. Leptothorax rugaiulus Emery. 

 South Dakota: (Rei'gande). 



Colorado: (Pergande); Cheyenne Canyon, near Colorado Springs 

 (Wheeler). 



Washington: Seattle (T. Kincaid). 



Montana: Helena (W. M. Mann). 



Study of much more material of this form and its varieties than 

 I possessed when I wrote my " Revision of the North American Ants 

 of the Genus Leptothorax" (Proc. Acad. Nat. Sci. Phila., 1903, pp. 

 215-260) convinces me that rugaiulus is really a distinct species, as 

 Emery maintained, and not a subspecies of curvispinosus Mayr. The 

 latter is the most generally distributed and abundant Leptothorax in 

 the Eastern and Central States as far west as Missouri, but rugatidus 

 and its varieties are confined to the W^estern States. The two forms 

 also differ in habits, rugaiulus and its varieties nesting under stones 

 and curvispinosus in hollow twigs and old galls. 



40. Leptothorax rugatulus var. cockerclli W^heeler. 



New Mexico: Las Vegas Hot Springs, type locality (T. D. A. 

 Cockerell). 



Arizona: Miller, Carr and Ramsav Canvons, Huachuca Mts. 

 (Biedermann, Mann and Wheeler). 



