their numerous varieties the precise analogues of the ancient volcanic rocks of Shropshire.
EXPLANATION OF PLATE XX.
2. Another portion of the same slice.
3. Part of a thin slice of perlite from Schemnitz.
4. Perlitic spheroid from Cabo de Gata. see p. 452.
5. Section of perlite from Schemnitz, showing parallel and cross joints, with general grouping of the perlitic spheroids, see p. 452.
6. Ancient perlitic pitchstone. "Lea Rock." near Wellington, showing a similar original structure. The shaded pans represent a green-coloured product of alteration, see p. 456.
7. Section of spherulitic perlite from Kremnitz, described p. 453.
8. Section of spherulitic pitchstone from Lea Rock, containing bands of spherulites and streams of mioroliths in a transparent perlitic matrix.
9. Diagram of spherulite, described p. 454.
10. Spherulite in ancient pitchstone, Lea Rock, containing two crystals of felspar, and traversed by a vein filled with a substance having similar optical characters to the devitrified matrix, see p. 457.
The figures faithfully represent the originals as seen with the magnifying powers indicated, with the exception of the fibrous crystallization of the spherulites, which is, of course, greatly exaggerated.
Discussion.
Mr. Warington W. Smyth thought that, with regard to the rocks of the Lizard Point. Mr. Bonney's paper would carry conviction to the minds of many who had been led to different views by the works of previous writers. The facts brought forward seemed to correlate these rocks with others which have been examined in Sweden and Norway, in the south of Spain, and in Elba.
Prof. Judd. referring to Mr. Allport's paper, said that the similarity of these ancient rocks to those of Tertiary times extended to the most minute details. The unity of character so long ago recognized among stratiried rocks of different ages was now being extended to the igneous rocks: and these also would in time be correlated according to their respective ages.
The President inquired whether Mr. Bonney had met with indications of gas-passages in the serpentinous rocks, such as might simulate Eozoon.
Rev. T. G. Bonney stated that he had examined the serpentines of Elba. With respect to Mr. McPherson's paper referred to, he said that some of that gentleman's figures might be taken as representing the Lizard serpentines. In reply to the President he stated that he had seen gas-passages, but nothing resembling Eozoon, although in the first stages of the decomposition of olivine the nummuline layer sometimes seemed to be simulated. For his own pair he believed in the organic nature of Eozoon.
