NATURE'S REALM. 9 
Sometimes one or more eggs of the warbler 
are sacrificed with the hated aliens, such is the 
detestation of these birds toward the inter- 
lopers. 
Several structures now before me exhibit the 
architectural skill displayed by these thought- 
ful birds in thus relieving themselves of an un- 
solicited addition to their family. As many as 
one nest in fifteen is thus built in order to en- 
tomb the objectionable eggs, and the incubus 
is a second time resisted in one instance, to my 
knowledge, thereby presenting the decidedly 
unusual condition, even in this anomalous re- 
lation, of a three-storied rest. During the 
early part of the construction a foolish cow 
bird, anticipating rather prematurely, laid an 
egg. This was soon covered and the nest 
finisned. Two eggs were then deposited to the 
credit of the happy warblers ere they were 
again cruelly imposed upon. Thinking that 
the neighborhood was moral and that nothing 
would occur to harm their house at the side of 
the road, the pair flitted about in their happi- 
ness and innocence of ill, little suspecting the 
designs of two crafty, dusky cow birds, which 
had skulked about for several days. Alas! 
when the joyous warblers returned they were 
greeted with the sight of two speckled eggs 
twice as large as their own, which were 
crowded out of place. After this imposition 
the determined pair, probably from former 
years’ experience, immediately began a second 
time to evade the encroachments of the spoli- 
ators. Without hesitation they immediately 
inhumed their own eggs with the unsought 
additions. When discovered their work ot 
love had advanced to that stage where the re- 
mainder of the clutch of eggs reposed in the 
upper story or nest of this remarkable struc- 
ture. The three eggs in the upper or nest 
proper were advanced in incubation, while the 
four eggs in the second story and one in the 
lower were still fresh, but doomed to destruc- 
tion from their position and the want of heat 
only supplied by the bird’s body. 
In those cases where the eggs of the cow bird 
are hatched the old yellow warblers, owners of 
the nest, are kind and attentive to the young 
aliens. The fond pair, though forced in their 
adoption, are generally devoted to these per- 
fidious children of fate up to the time of their 
departure from their alien home. 
As late summer draws on the handsome 
yellow warbler is more rarely seen and heard, 
the little fellow keeping himself concealed in 
the low bushes about the streams, occasionally 
enlivening the scene by flitting through one of 
the vistas of the willow copse, when it will be 
noticed that his plumage, after the recent 
moulting, is not so bright as in early summer. 
As the golden rod rears its golden racemes to 
our view in the rank grass at the roadside the 
warbler becomes scarcer, and, by the time that 
the pleasing autumn flowers are in their glory, 
the little yellow meteors have all left us for 
their seven to eight months’ vacation in the 
sunny south. 
A TRUE GLACIER IN MEXICO. 
Prof. Heilprin’s party, who have been explor- 
ing in Mexico and Yucatan for four months 
past, under the direction of the Philadelphia 
Academy of Sciences, has recently returned 
chock full of delightful success and new infor- 
mation in all departments of natural history. 
On Mount Ixtaccihuatl, which is the third high- 
est mountain in Mexico, was found a true gla- 
cier. Although the wreck of a true volcano it 
no longer presents the form of a symmetrical 
volcanic cone, but exhibits a long broken crest 
upon which snow and ice have accumulated to 
a thickness of from 75 to 100 feet. Enormous 
crevasses traverse this ice in all directions and 
make the ascent in combination with the very 
deep slope of the mountain, one of great diffi- 
culty and no inconsiderable danger. The ice 
is, in fact, a new moving glacier, and presents 
all the features which distinguish the glaciers 
of the Alps. It has been supposed hitherto 
that glaciers were completely wanting in 
Mexico. 
