nd the event must be very
rare, for an instance in Germany has been thought worth recording.[340]
In Paraguay the native Nasua, though kept in pairs during many years
and perfectly tamed, has never been known, according to Rengger, to
breed or show any sexual passion; nor, as I hear from Mr. Bates, does
this animal, or the Cercoleptes, breed in the region of the Amazons.
Two other plantigrade genera, Procyon and Gulo, though often kept tame
in Paraguay, never breed there. In the Zoological Gardens species of
Nasua and Procyon have been seen to couple; but they did not produce
young.

As domesticated rabbits, guinea-pigs, and white mice breed so
abundantly when closely confined under various climates, it might have
been thought that most other members of the Rodent order would have
bred in captivity, but this is not the case. It deserves notice, as
showing how the capacity to breed sometimes goes by affinity, that the
one native rodent of Paraguay, which there breeds _freely_ and has
yielded successive generations, is the _Cavia aperea_; and this animal
is so closely allied to the guinea-pig, that it has been erroneously
thought to be the parent-form.[341] In the Zoological Gardens, some
rodents have coupled, but have never produced young; some have neither
coupled nor bred; but a few have bred, as the porcupine more than once,
the Barbary mouse, lemming, chinchilla, and the agouti (_Dasyprocta
aguti_), several times. This latter animal has also produced young in
Paraguay, though they were born dead and ill-formed; but in Amazonia,
according to Mr. Bates, it never breeds, though often kept tame about
the houses. Nor does the paca (_Coelogenys paca_) breed there. The
common hare when confined has, I believe, never bred in Europe;[342]
though, according to a recent statement, it has crossed with the
rabbit. I have never heard of the dormouse breeding in confinement. But
squirrels offer a more curious case: with one exception, no species has
ever bred in the Zoological Gardens, yet as many as fourteen
individuals of _S. palmarum_ were kept together during several years.
The _S. cinerea_ has been seen to couple, but it did not produce young;
nor has this species, when rendered extremely tame in its native
country, North America, been ever known to breed.[343] At Lord Derby's
menagerie squ