434 ANTS. 



summers, I failed to find any traces of the Syinniynnica. We must 

 conclude, therefore, that this ant is either very rare or very local. As 

 it may be said to represent an archaic form of Formicoxcnus, it is 

 possible that this European ant was once a guest of M. rubida, which 

 is closely related to M. inntica, and only later became associated with 

 / ; . rnfa. This is suggested by the fact that the present host belongs 

 to a different subfamily and by the extreme ergatomorphism of the 

 males. This specialization is, at any rate, an interesting example of 

 the more advanced state of development of European as compared with 

 North American species belonging to the same or allied genera. 



9. Leptothorax cnicrsoni (Fig. 261). This boreal ant is known 

 only from the mountains of New England, but there can be little doubt 

 that it occurs also in eastern British America. I found it first in the 

 Litchfield and Berkshire Hills. Mrs. A. T. Slosson has since taken it 

 on the summit of Mt. Washington and I have found it also at South 

 Harpswell, Maine. It lives only in xenobiosis with another boreal ant, 

 Mynnica canadcnsis, a variety of M. brci'inodis. I have described 

 the habits of these ants at length in two papers ( 1901 c, I9O3/), 

 to which the reader is referred ; here only the more essential particu- 

 lars need be mentioned. M.. catiadensis builds its nest in the soil of 

 bogs, in clumps of moss (Polytrichum) or under logs and stones, and 

 the Leptothorax excavates small cavities near the surface and commu- 

 nicating by means of short, tenuous galleries with those of its host. 

 The broods of both species are brought up separately. The Lepto- 

 thorax, though consorting freely with the Mynnica workers in their 

 galleries, resents any intrusion of these ants into its own chambers. 

 The inquilines do not leave the nest to forage but obtain all their food, 

 in a very interesting manner, from their hosts. Both in the natural 

 and artificial nests the Leptothorax are seen to mount the backs of the 

 Myrmicas and to lick or shampoo their surfaces in a kind of feverish 

 excitement. This shampooing has a two-fold object: to obtain the 

 oleaginous salivary secretion with which the Myrmicas cover their bodies 

 when they clean one another, and to induce these ants to regurgitate 

 the liquid food stored in their crops. The Leptothorax devote most of 

 their time to licking the heads and clypei of their nest mates, stopping 

 from time to time to imbibe the liquid food from their lips. Whenever 

 the Mynnica workers return to the nest after visiting the aphids on the 

 neighboring plants, they are intercepted by the Leptothorax and com- 

 pelled to pay toll in this comical manner. The Mynnica always treat 

 their little guests with the greatest consideration and affection. In 

 Lubbock nests they are often seen to break into the Leptothorax cham- 

 bers, as if seeking an opportunity to be shampooed. On such occa- 



