Note 244 — Chapter XIII · THE ERUPTIONS OF LLANDEILO AND BALA AGE
Reading edition
Monthly Microscopical Journal, 1877, p. 246.
[245] Geol. Mag. 1891, p. 538.
[246] Quart. Journ. Geol. Soc. vol. xlix. (1893), p. 389. Mr. Harker, op. cit. vol. xlvii. (1891).