1. Hirst, S., and Maulik, S., Geol. Mag., 63, 69 (1926).
2. Tillyard, E. J., Trans. Entomol. Soc., 65 (1928).
3. NATURE, 139, 334 (1937).
4. Scourfleld, D. J., Proc. Linn. Soc. Lond., April 25, 1940, p. 113.
5. Folsom, J. W., Univ. Toronto Studies, Geol. Series, 40 (1937).