NATTERER’S BAT. 243 
wall (A. Newton, Zool. 1853, p. 3804), and from the roof of a 
church (Bell, Brit. Quad., 2nd ed., p. 55). 
Like other Bats it is gregarious, and has occasionally been 
found in large colonies. A notable instance of this is mentioned 
in ‘The Zoologist’ for 1853 (p. 4012), where Dr. Kinahan 
records the fact of 27, 85, and 58 having been counted while 
issuing from one and the same hole in the abutment of Tankards- 
town Bridge, which crosses the River Barrow at Levitstown, on 
the confines of Kildare and Queen’s County. 
The almost entire disappearance of Bats during the winter, 
unless tempted forth by unusually mild or warm weather, has led 
to the belief in some quarters that they migrate like birds, 
though it is certain that their absence in most cases is to be 
accounted for by their hybernation. But something very like 
migration has been observed, if not actually proved. It has been 
ascertained by Blasius that Bats not merely seek for a change of 
locality, but that they do so with such regularity that it becomes, 
in his opinion, a “ migration.” Bell, apparently loth to accept 
this view, remarks (op. cit., p. 9), “‘ May we not suppose that the 
migration of Bats observed by Professor Blasius was the mere 
unconscious appearance, night after night, of these creatures at 
a spot somewhat removed from that of the previous night, thus 
following the twilight, rather than what may be properly termed 
a migration?’ There is other evidence, however, besides that 
of Blasius, to which he has not referred. 
Spallanzani discovered that in Italy a great many Bats, 
especially Vespertilio murinus, migrate at the approach of cold 
weather. At Pavia there are no grottoes nor caverns to which 
they can retire, and not a single Vespertilio could be found in 
winter, though no pains were spared in searching for them. The 
latest date at which he observed Bats flying at Pavia was Nov. 2, 
when the thermometer was at 55°. Another species, V. equinus, 
was seen at Modena on Nov. 4th. None were then observed 
again until March, when the temperature was 45°, and then 
V. equinus had not reappeared, the weather being too cold for it ; 
for some species are quite torpid at a temperature which others 
are able to endure without their muscular energy being 
diminished.* 

* Spallanzani, ‘ Rapports de l’air avec les étres organisés,’ il. p. 125. 
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