a DP 
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Ants’ Nests and their Inhabitants. 683 
division into two groups: æ. Those species from which it is tol- 
erably certain that the ants derive some benefit; and 4. Those of 
which nothing at all is known. 
The only benefit that is known to be derived by the ants from 
any of the species is in the shape of a (probably) sweet secretion. 
Prominent among these are the species of Cremastochilus, most 
of them of immense size compared to that of the ants with 
which they live. These insects have a glandiferous surface 
at the hind angle of the thorax covered with a thin plate, and 
several specimens have been observed where this plate has been 
gnawed off by the ants to facilitate their getting at the secretion 
of the glands. These species, as stated, are of large size, and 
whole squads of ants have been observed in the task of prevent- 
ing the escape of an individual that had apparently become tired 
of its quarters. 
This practice of the ants has been but recently discovered, and 
nearly created a new species. The hind angles of the thorax are 
characteristic in form, and systematists have used them to sepa- 
tate the species. When the first specimen was found without any _ : 
angles at all, of course it was thought that here was an entirely de 
new species, and only the fortunate discovery of other specimens 
in which the angles were only partially eaten off, or missing only 
4 on one side, prevented a synonym or two. : 
: There is an immense difficulty in the way of getting at the 
| habits of these inquilines. Not only is it a difficult task in the 
| first place to find them, but when the nests are disturbed every- Ys 
thing is thrown out of its usual course, and ants and guests dis- 
appear in the same galleries under ground, from which it is impos- _ 
sible to dislodge them. Artificial nests have been constructed in 
Europe, and it has been observed that the ants appeared to lick 
certain bristly tufts in Claviger, which have been assumed to be 
Secretory organs. A number of the species in our fauna have sim- 
"ar tufts and they probably serve a similar purpose. They appear — 
in all parts of the body and are very variable in extent. Many spe- 
cies, however, still remain about which absolutely nothing is 
known, and which have no structures which may be assumed to be 
Secretory. Many years ago it was observed that Claviger was 
ix, 
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oy 7 
fa Fe 
