﻿478 MESSES. WHITE AND TREACHER ON THE [Aug. 1905, 



and which there are independent reasons (drawn from an examina- 

 tion of a much wider area) for assigning to horizons well below the 

 upper limit of the zone at its full development. 



The lithological distinction between the lowest division of this 

 section and other cor-anguinnm-beds occurring at a similar, a 

 greater, or a less distance below the base of the Tertiaries in the 

 neighbouring exposures, is much more pronounced. The fine 

 texture of the chalk, the total absence of flints, the presence of 

 small phosphatic concretions, and the unusual prominence of fish- 

 remains and coprolites, in the upper 14 feet of this division 

 (excluding the contents of the borings), are characters which serve 

 at once to separate it from those beds, and to ally it to the succeeding, 

 richly-phosphatic, MarsKjntes-atr&ta. 



The lithological relations of the Lower White Chalk to the 

 overlying beds seem to us to warrant its inclusion in the phosphatic 

 series ; while these relations, together with its palseontological 

 characters, render the former existence of any considerable thickness 

 of higher cor-dnguinum-heds between it and the Lower Brown 

 Chalk with Uintacrinus improbable. 



The Marsupites-Be&s. — Turning to the Marsupites-Beds, it 

 is evident that in the Lower Brown Chalk (B) we have the repre- 

 sentative of the Uinta crinus-Bemd, or of some portion of it. Here, 

 as in the type-section of that band, the eponymous crinoid is 

 associated with Actinocamax verus and Kingena lima ; but many of 

 the characteristic and. common forms of the Thanet cliffs and other 

 exposures find no place in the list given above. Some of these 

 apparently-missing fossils, such as the large dome-shaped Ecliino- 

 corys scutatus and the bryozoa, may be present in a comminuted 

 condition. Others, less fragile, as, for instance, the large Poro- 

 sphcera globularis, the nipple-calyxed Bourgueticrinus, and Tere- 

 bratulina Rowei, if not wanting, must be exceedingly scarce. We 

 do not, however, pretend to have exhausted the possibilities of this 

 division. Owing to the colour and adherent nature of the brown 

 chalks, few of their smaller fossils are visible, much less recognizable, 

 on the face of the pit or in detached blocks, and the bulk of those in 

 our collection were obtained by the tedious processes of sifting and 

 washing. 



It need scarcely be pointed out that the occurrence of Marsujntes 

 so near the base of its zone is most unusual in this country. 



The restriction of Actinocamax verus to the base of the Lower 

 Brown Chalk establishes another parallel between the Phosphatic 

 Chalks of Taplow and Picardy, for MM. A. de Grossouvre, 1 

 J. Gosselet, 2 and H. Lasne 3 observe the same thing in many 

 workings near Doullens and elsewhere. 



1 Bull. Soc. Geol. France, ser. 3, vol. xxii (1894) p. lviii; & ibid. vol. xxvii 

 (1899) p. 129. 



2 Ann. Soc. Geol. du Nord, vol. xxx (1901) p. 210 ; & ibid. vol. xxxi (1902) 

 p. 60. 



3 Ibid. vol. xxxi (1902) pp. 57-59 ; and Bull. Soc. Geol. France, ssr. 3, 

 vol. xx (1892) pp. 223-24. 



