724 THE AMERICAN NATURALIST. 
doubt that it must have been formed by alliance between.two 
or more queens representing the two distinct color varieties. 
The whole country about Aguas Calientes is covered with the 
most flourishing nests of these two forms, often very close to 
each other, so that it is not at allimprobable that an occasional 
mixed nest should arise in this manner. 
30. Stenamma tennesseense Mayr and S. fulvum Roger, subsp. aquia 
Buckley, var. piceum Emery. 
Rev. P. J. Schmitt found this singular mixed nest near 
Beatty, Pa. The queen of the colony belonged to S. tennes- 
seense. Rev. Mr. Schmitt was impressed by the fact that the 
nest was under a stone, whereas /ennesseense normally occurs 
only in dead wood at Beatty. This seems to be generally true 
of the species. In Illinois and Wisconsin I have never taken 
it except in the old logs in the rather open forests. It is a 
singular fact that in this and in nearly all the other cases of 
synclerobiosis the two consociating species or varieties repre- 
sent a light and a dark colored form. This can scarcely be a 
mere coincidence, but I am unable to suggest any explanation 
of this peculiar phenomenon. 
I cannot conclude this portion of my paper without express- 
ing my indebtedness to Rev. P. J. Schmitt and to Professor 
Auguste Forel. These gentlemen have most generously sent 
me specimens of several of the rare and peculiar Formicide 
which I have figured. 
(To be continued.) 
! A somewhat similar mixed nest appears to have been found by Mapi 
(78, p. 37, footnote) at Mentone. This colony consisted of nearly equal aper ; 
Stenamma [s. gen. Messor] structor, barbara, and the red-headed variety 9 
barbara. 
