536 THE AMERICAN NATURALIST. [Vor. XXXV. 
European Formicoxenus nitidulus, which has been carefully 
studied by Adlerz (84), Forel (74,'86), Wasmann (91), and 
Janet (97). It is a singular fact that, notwithstanding all these 
valuable observations, the feeding habits of the Formicoxenus 
have never been observed. As this ant, in certain particulars, 
4 , Strikingly resembles Leptothorax em- 
ersont, Janet's résumé (97, pp. 54-56) 
of what is known concerning its 
behavior may be quoted before re- 
cording the little that is known con- 
cerning our American guest ants. 
* Formicoxenus nitidulus is a pretty 
little species of very timid character. 
Forel found it to be a rare insect in 
Switzerland. I have several times 
taken small colonies of it at Beauvais. 
Wasmann mentions it as very com- 
mon in Holland.  Adlerz found it 
abundant in southern Sweden. Itis, 
therefore, a north European species. 
The worker scarcely reaches a length 
of 3 mm., and the queen is but little 
larger. The male (Fig. 12), discovered 
by Adlerz (84), is apterous like that 
of Anergates atratulus and like one 
of the male forms of Ponera puncta- 
tissima. Its shape, color, and the 
absence of wings make it difficult 
to distinguish from the worker. It 
Vie ini ormicosema nitidulus Ny. may, nevertheless, be recognized 
ale (after Adlerz). 
from other external male characters. 
Its antennz are more strongly recurved at their tips and 
are 12-jointed ; że., they have one more joint than the female 
phases (either queen or worker) In the abdomen five seg- 
ments (the 7th to 11th) are visible from the exterior instead 
of four (segments 7 to 10) as in the females. The mandibles 
are smaller; the ocelli are well developed. The relations of 
Formicoxenus nitidulus to its host have been especially studied 
