The Use of Gryphaea in the Correlation of the Lower Lias

^{page 256 note 1} Hatch, , “The Boulder Beds of Ventersdorp, Transvaal”: Trans. Geol. Soc. S.A., vol. vi, 1903, p. 95.

^{page 256 note 2} Molengraaf, , “A hitherto unrecognized Formation underlying the Black Reef series”: Trans. Geol. Soc. S.A., vol. vi, 1903, p. 68.

^{page 257 note 1} See Jackson, R. T., “Phylogeny of the Pelecypoda: The Aviculidæ and their Allies”: Mem. Boat. Soc. Nat. Hist., vol. iv, 1890, p. 317. Kitchin, F. L., “Summary of Progress”: Geol. Survey, 1911. Davies, A. Morley, An Introduction to Palæoniology, 1920, p. 89.

^{page 257 note 2} See, for example, Hébert, M., “Observations sur les Gryphées du Lias, etc.”: Bull. Soc. Geol. France., ser. II, vol. xiii, 1855, p. 213; and Terquem, O., “Palénntologie de l' Etage Inférieur de la Formation Liasique, etc.”: Bull. Hoc. d'hist. nat. de. la Moselle, ser. II, vol. v, 1855.

^{page 257 note 3} Jones, John, “On Cryphsea Incurva and its Varieties ”: Proc. Cottes. Nat. Club, vol. iii, 1865, pp. 81–95.

^{page 257 note 4} Buckman, S. S., “Jurassic Chronology: I. Lias”: Quart. Journ. Geol. Soc., vol. lxxiii, 1918. p. 274.

^{page 257 note 5} Tutcher, J. W., ibid., pp. 278–81.

^{page 260 note 1} Thompson, D'arcy Wentworth, On Growth and Form, 1917, p. 531.

^{page 261 note 1} Among Liassic Gastropoda, and some families of Ammonites, it is not uncommon to find adult specimens at the same horizon at somewhat different stages of evolution; some are more “highly accelerated” than others. The differences between the Gryphaeas, however, are much more apparent.

^{page 262 note 1} The very curved forms from the angulata zone generally differ from G. incurva in having a feeble sulcus (if any) and a larger area of attachment. They are, therefore, accelerated in some characters only.

^{page 264 note 1} The parallel evolution of these numerous series, each passing almost inevitably through comparable stages, and following what may be regarded, as a pre-determined “programme”, affords an example of what Dr. F. L. Kitchin has called “programme-evolution”. (See Lang, W. D., Catalogue Cret. Bryozoa, vol. iii, 1921, p. xviii.)

^{page 265 note 1} As in the type of G. incurva.

^{page 265 note 2} Lang, W. D., Catalogue of Cretaceous Bryozoa, vol. iii, 1921, p. x.

^{page 265 note 3} Jackson, R. T., loc. cit., p. 312.

^{page 266 note 1} Trueman, A. E., “The Liassio Rocks of the Cardiff District”: Proc. Geol. Assoc., vol. xxxi, 1920, p. 102.

^{page 266 note 2} Vaughan, A. & Tutcher, J. W., “The Lias of the Neighbourhood of Keynsham”: Proc. Brist. Nat. Soc., N.S., vol. x, 1903.

^{page 268 note 1} Richardson, L., “The Section of Lower Lias at Hock Crib, Fretherne, Glos.”: Proc. Cuttes. Nat. F.C., vol. xvi, 2, 1908, pp. 135–42.