272 Bulletin American Museum of Natural History. [Vol. XXI, 



found in the nest. They were under a large flat stone, the edges of 

 which they had banked with vegetable debris after the manner of F. 

 difflcilis and its var. consocians. During the past summer (June 30, 

 1905), on again visiting the colony, I found it to contain several of the 

 minute females (mostly callow), and was thus able to satisfy myself 

 that it represented a distinct and un described species. Numerous 

 workers, together with many cocoons, were kept for several weeks in 

 an artificial nest. Dozens of the tiny females but only two males 

 hatched during the first week in July. No workers hatched till July 

 9, when they appeared in great numbers. The small size of the female 

 seems, therefore, to be correlated with more precocious development 

 than in our common species of Formica. The movements of the 

 workers are extremely active and petulant, contrasting with the move- 

 ments of such forms as F. integra, consocians, etc., and resembling 

 those of F. sanguinea. The females are more phlegmatic except when 

 greatly excited. The approximate date of the nuptial flight is July 1 1 . 

 At any rate, during the early morning hours of that day most of the 

 females managed to escape and ascended to the ceiling of the room in 

 which I had placed their artificial nest. The diminutive size of the 

 females strongly indicates reduced or belated fertility, so that this 

 species, like F. difflcilis and its var. consocians, F. microgyria, nevaden- 

 sis, and montigena, very probably establishes its colony with the aid of 

 workers belonging to some other species of Formica. I suspect that 

 F. subpolita var. neogagates is the ant used for this purpose, as its 

 workers so closely resemble the female nepticula both in size and 

 coloration. I find, moreover, that a small colony of neogagates workers 

 can be induced to adopt a dealated female nepticula. 



4. Formica nevadensis Wheeler. 



F. microgyna var. nevadensis Wheeler, Bull. Am. Mus. Nat. Hist., 

 Vol. XX, Oct. II, 1904, p. 373. ?. 



Since both the worker and female of F. nepticula are known, it 

 is no longer probable that nevadensis should be attached as a variety 

 to microgyna. The female nevadensis has a very smooth and shining 

 gaster and this is probably also the case in the unknown worker, 

 which would thus differ decidedly from the opaque-bodied worker 

 of microgyna. I believe, therefore, that we are justified in raising 

 nevadensis to specific rank. The discovery of the worker of this form 

 will enable us to decide whether nepticula is to be regarded as an inde- 

 pendent species or merely as an eastern subspecies of nevadensis. 



