shell sand. I have
seen among the Hebrides a shell sand accumulated along the beach to the
depth of many feet, of which fully two thirds was composed of the valves
and compartments of balanidae; and a similar sand on the east coast of
Scotland, a little to the south of St. Andrews, formed in still larger
proportions of the fragments of a single species,--_Balanus crenatus_.
Now, this genus, so amazingly abundant at the present time in every
existing sea, and whose accumulated remains bid fair to exist as great
limestone rocks in the future, had no existence in the Palaeozoic or
Secondary ages. It first appears in the times of the earlier Tertiary,
in, however, only a single species; and, becoming gradually of more and
more importance as a group, it receives its fullest numerical
development in the present time. And thus the remains of a sub-class of
animals, low in their standing among the articulata, may form one of the
most prominent Palaeontological features of the human period. But enough
for the present of circumstance and detail.

[Illustration: Fig. 84.

MUREX ALVEOLATUS.

(_Red Crag._)]

[Illustration: Fig. 85.

ASTARTE OMALII.

(_Red Crag._)]

[Illustration: Fig. 86.

BALANUS CRASSUS.

(_Red Crag._)]

Such, so far as the geologist has yet been able to read the records of
his science, has been the course of creation, from the first beginnings
of vitality upon our planet, until the appearance of man. And very
wonderful, surely, has that course been! How strange a procession! Never
yet on Egyptian obelisk or Assyrian frieze,--where long lines of figures
seem stalking across the granite, each charged with symbol and
mystery,--have our Layards or Rawlinsons seen aught so extraordinary as
that long procession of being which, starting out of the blank depths of
the bygone eternity, is still defiling across the stage, and of which we
ourselves form some of the passing figures. Who shall declare the
profound meanings with which these geologic hieroglyphics are charged,
or indicate the ultimate goal at which the long procession is destined
to arrive?

The readings already given, the conclusions already deduced, are as
various as the hopes and fears, the habits of thought, and the cast of
intellect, of the several interpreters who have set themselves,--some,
alas! with but little preparation and very imperfect knowledge,--to
declare in their order the details of this marvellous, dream-like
vision, and, wi