friction has had something to do with the disappearance of the external
portion of the tail, is not so ridiculous as it at first appears. Dr.
Anderson (92. Proceedings Zoological Society, 1872, p. 210.) states
that the extremely short tail of Macacus brunneus is formed of eleven
vertebrae, including the imbedded basal ones. The extremity is
tendinous and contains no vertebrae; this is succeeded by five
rudimentary ones, so minute that together they are only one line and a
half in length, and these are permanently bent to one side in the shape
of a hook. The free part of the tail, only a little above an inch in
length, includes only four more small vertebrae. This short tail is
carried erect; but about a quarter of its total length is doubled on to
itself to the left; and this terminal part, which includes the
hook-like portion, serves to fill up the interspace between the upper
divergent portion of the callosities; so that the animal sits on it,
and thus renders it rough and callous. Dr. Anderson thus sums up his
observations: These facts seem to me to have only one explanation;
this tail, from its short size, is in the monkey s way when it sits
down, and frequently becomes placed under the animal while it is in
this attitude; and from the circumstance that it does not extend beyond
the extremity of the ischial tuberosities, it seems as if the tail
originally had been bent round by the will of the animal, into the
interspace between the callosities, to escape being pressed between
them and the ground, and that in time the curvature became permanent,
fitting in of itself when the organ happens to be sat upon. Under
these circumstances it is not surprising that the surface of the tail
should have been roughened and rendered callous, and Dr. Murie (93.
Proceedings Zoological Society, 1872, p. 786.), who carefully
observed this species in the Zoological Gardens, as well as three other
closely allied forms with slightly longer tails, says that when the
animal sits down, the tail is necessarily thrust to one side of the
buttocks; and whether long or short its root is consequently liable to
be rubbed or chafed. As we now have evidence that mutilations
occasionally produce an inherited effect (94. I allude to Dr.
Brown-Sequard s observations on the transmitted effect of an operation
causing epilepsy in guinea-pigs, and likewise more recently on the
analogous effects of cutting the sympathetic nerve in the neck. I shall
hereafter have occasion to refer to Mr. Salvin s interesting case of
the apparently inherited effects of mot-mots biting off the barbs of
their own tail-feathers. See also on the general subject Variation of
Animals and Plants under Domestication, vol. ii. pp. 22-24.), it is
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