to the cavern having been a sort of family vault. Again, M. Dupont
found thirty per cent. of perforated bones in the caves of the Valley
of the Lesse, belonging to the Reindeer period; whilst M. Leguay, in a
sort of dolmen at Argenteuil, observed twenty-five per cent. to be
perforated; and M. Pruner-Bey found twenty-six per cent. in the same
condition in bones from Vaureal. Nor should it be left unnoticed that
M. Pruner-Bey states that this condition is common in Guanche
skeletons. It is an interesting fact that ancient races, in this and
several other cases, more frequently present structures which resemble
those of the lower animals than do the modern. One chief cause seems to
be that the ancient races stand somewhat nearer in the long line of
descent to their remote animal-like progenitors.
In man, the os coccyx, together with certain other vertebrae hereafter
to be described, though functionless as a tail, plainly represent this
part in other vertebrate animals. At an early embryonic period it is
free, and projects beyond the lower extremities; as may be seen in the
drawing (Fig. 1.) of a human embryo. Even after birth it has been
known, in certain rare and anomalous cases (52. Quatrefages has lately
collected the evidence on this subject. Revue des Cours
Scientifiques, 1867-1868, p. 625. In 1840 Fleischmann exhibited a
human foetus bearing a free tail, which, as is not always the case,
included vertebral bodies; and this tail was critically examined by the
many anatomists present at the meeting of naturalists at Erlangen (see
Marshall in Niederlandischen Archiv fur Zoologie, December 1871).), to
form a small external rudiment of a tail. The os coccyx is short,
usually including only four vertebrae, all anchylosed together: and
these are in a rudimentary condition, for they consist, with the
exception of the basal one, of the centrum alone. (53. Owen, On the
Nature of Limbs, 1849, p. 114.) They are furnished with some small
muscles; one of which, as I am informed by Prof. Turner, has been
expressly described by Theile as a rudimentary repetition of the
extensor of the tail, a muscle which is so largely developed in many
mammals.
The spinal cord in man extends only as far downwards as the last dorsal
or first lumbar vertebra; but a thread-like structure (the filum
terminale) runs down the axis of the sacral part of the spinal canal,
and even along the back of the coccygeal bones. The upper part of this
filament, as Prof. Turner informs me, is undoubtedly homologous with
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