1865.. WHITAKEE BXrCKlNGHAM CHALK, 399 I cannot give the thickness with accuraC3\ I will now give a short account of each, beginning with the lowest. (g). Chalk-marl. — A rather brownish-white, slightly sandy, clayey chalk, fissile, with stony layers here and there, and often with fossils (notably fish-scales). This is per- haps 80 feet thick, and mostly causes a rise of the ground above the sloping plain of the Upper Green- sand. (/). Totfernlioe Stone.- At the top of the Chalk- marl in this district there are generally two layers of rathersandy limestone, separated by a little marl, and which are more dis- tinct further north-east- ward (in Bedfordshire), where they are each about 3 feet thick. One bed is always here present, but I did not always see the two. This stone mostly yields fossils, amongst which Ammonites vai'ians and an Inoceramus are abundant, and small, hard,dark-brown nodules, most likely coprolitic : it is harder and darker than common chalk, and con- tains many small dark grains ; and was once largely quarried, for build- ing, at Totternhoe, where there are plentiful traces of the workings. Most of the old churches of the neighbourhood were built in great part of this pe- rishable stone, but I be- lieve that its use has been long discontinued. Details of the occur- rence of this bed will be given in the ' Gcolo- 2 E 2