clearer comprehension of his subject. The field of Geology is a wide and varied one, and whatever may help to a sounder appreciation of its importance, or induce another labourer to enter, however trivial it may appear to the practised worker, should at least have the opportunity of doing so by being put in the requisite form and addressed to the proper quarter.

EDINBURGH, GILMORE PLACE,
April 1869.

D. P.

RAIN-PRINTS, SUN-CRACKS, RIPPLE-MARKS, FOOT-PRINTS,

BRITISH STRATIFIED SYSTEMS,

TO WHICH THE FOLLOWING SKETCHES MORE ESPECIALLY REFER.

The subjoined tabulation exhibits the arrangement of the British stratified rocks, as accepted by our leading geologists-minor and local devia-tions of superposition being subordinated for the sake of distinct comprehension and ready reference :

10

ORDER AND SUCCESSION OF LIFE,

ESPECIALLY AS REFERRED TO IN THE FOLLOWING SKETCHES.

The subjoined tabulation exhibits proximately the stages at which the great ascending sections of Plants and Animals make their first appearance in the stratified systems :

Marsupial mammals, birds, rep-
tiles, fishes, shell-fish, crus-
tacea, zoophytes; palms,
cycads, coniferæ, ferns, ly-
copods, sea-weeds.

Reptiles, fishes, shell-fish, crus-
tacea, zoophytes; coniferæ,
ferns, lycopods, sea-weeds.
Fishes, shellfish, crustacea,
zoophytes; ferns, lycopods,
sea-weeds.

Shellfish, crustacea, worm -
tracks, zoophytes; sea-weeds.
Crustacea, worm-burrows, and
zoophytes.

Traces of lowly or foramini-
feral organisms.