In reference to the correspondence on my speculations in theoretical geology and astronomy which have been printed in this Journal, I wish to take this opportunity of saying, that if in the cases of the Rev. O. Fisher, p. 54 in this volume, and of Dr. Leslie, p. 295 in Vol. VI., I have inserted such comments on any of the physical hypotheses to which from time to time I have given expression without replying to those comments, that I do not therefore acknowledge my opponents to be right, nor, on the other hand, do I intend to pass them over slightingly as wrong, or as unworthy of attention. I simply thought it best not to get into controversy while my own ideas were being enunciated. I cannot, however, concur in the Rev. O. Fisher's views as to the possibility of the earth's velocity, if initial primarily, being maintained, nor of a larger orbit for our planet being a result of any retardation of her motion. I am well aware of Kepler's law referred to, and I have my own opinion both of its value and its application. Mathematics may derive a result from a given basis, but mathematics never yet gave birth to a basis of facts.

It is certainly very much out of stratigraphical order to jump from the fossil bird-remains of the Stonesfield Slate to those of the Tertiary beds of the Paris basin ; nor is such a step in any accordance with historical order. We aro simply compelled to take it, through the necessity of saying a few words in explanation of certain plates which have been issued with the previous numbers of this volume. The gap, however, in the historical series is not so very wide; and it is by no means useless in this place to run over afresh the review which the great Cuvier made of the labours of his predecessors. A section of vol. iii. of his famous work, ‘Recherches sur les Ossements Fossiles,’ published in 1812, was devoted to the remains of birds. “Naturalists,” he begins, “ are agreed that, of all animals, birds are those whose bones or other relics are the most rarely found in the fossil state. Some even absolutely deny that any have ever been met with; and indeed, by one of those singular accidents reserved for the beds of gypsum of our neighbourhood, there are scarcely any other well preserved fossil bones of birds than those they have furnished.” He then, to show the correctness of this statement, and the then recent knowledge even of the fossil birds of the platriàres of Paris, glances over the statements of Walch, Hermann, Camper, Blumenbach, Faujas, Lamanon, Gesner, Luid, Wallerius and Linnaeus, Davila and others, the accounts of most of which have been already given in our previous articles.

The following sketch of the glacial deposits of Furness is not pretended to be complete ; it is, in fact, nothing but a sketch: neither can it presume to be free from errors. The marine drift, especially, has not received all the attention it demands, but will, I hope, with the clays and peats of Furness, form a subject for a future memoir. The deposits in the section are referred doubtfully to their periods.

Striated Bock Surfaces.—The district of Furness; its south-eastern part, however, does not perhaps present so many of those remarkable records of the glacial period, the striated rock-surfaces, as are to be met with in more mountainous districts. The rocks, especially the Carboniferous Limestone and Permian formations, either lie in agreat measure hidden under a thick covering of deposits, or, as in the hills of the Upper Silurian strata, are of such a soft decomposing nature, that they retain very little primitive facing.

Occasionally, however, striations may be found. A little way in shore, west from the estuary of the Crake, at the head of Morecambe Bay, a rock-surface recently exposed by the removal of the overlying material, and now quarried away, showed a series of parallel shallow groovings from an inch to an inch and a half apart; the intervening spaces plane and smoothed, and having very fine striæ. The striæ and grooving had a direction from E. to W., or perhaps a little N.E. to S.W.