The Descent of Man

than the whole body, and is formed of twentyfour
vertebrae; in others it consists of a scarcely
visible stump, containing only three or four
vertebrae. In some kinds of baboons there are
twenty-five, whilst in the mandrill there are ten
very small stunted caudal vertebrae, or, according
to Cuvier (90. Mr. St. George Mivart, 'Proc.
Zoolog. Soc.' 1865, pp. 562, 583. Dr. J.E. Gray,
'Cat. Brit. Mus.: 'Skeletons.' Owen, 'Anatomy of
Vertebrates,' vol. ii. p. 517. Isidore Geoffroy,
'Hist. Nat. Gen.' tom. ii. p. 244.), sometimes
only five. The tail, whether it be long or short,
almost always tapers towards the end; and this,
I presume, results from the atrophy of the terminal
muscles, together with their arteries and
nerves, through disuse, leading to the atrophy
of the terminal bones. But no explanation can at
present be given of the great diversity which
often occurs in its length. Here, however, we
are more specially concerned with the complete
external disappearance of the tail. Professor
Broca has recently shewn (91. 'Revue d'Anthro-