IN THE ANGLO-PARIS BASIN 125 



this zone into two ; the zone of Euhoplites alphalautus (1926a ; 154 footnote 1) to 

 include Beds V and VI, and that of Anahoplites daviesi to include Bed VII (see also 

 1925b ; 34-35). Within a few months he realised that E. alphalautus was a form of 

 the varicosum Subzone, and substituted for it Euhoplites lautus and E. nitidus (1926b ; 

 425). Breistroffer (1965 ; table opp. 312) has grouped the nitidus and daviesi Sub- 

 zones as Subzone of nitidus -\- cornutum -\~ daviesi. This view is probably influenced 

 by the section near Wissant where the daviesi Subzone was thought to be present, but 

 where it is now known to be absent (p. 85). 



In England, the best known development is at Folkestone where the relationship 

 with the meandrinus Subzone below and the daviesi Subzone above is well seen (p. 15). 

 In France, the Subzone is well represented at Wissant but the sediments there are 

 marked by erosion levels at the base and the top (p. 84). The Subzone is not known 

 to be represented elsewhere in France at this time. The base of the Subzone is 

 marked by the general adoption of a channelled venter by the various species of the 

 genus Euhoplites. The ammonite fauna of the Subzone has been discussed by Owen 

 (1958 ; 154) and Hancock (1965 ; 246) and there is nothing further to add except that 

 the top of the Subzone is now drawn at Folkestone at the level within Bed VII 

 immediately below the first appearance of Anahoplites daviesi in the sequence. 



(i) Subzone of Anahoplites daviesi 



This Subzone recognised by Spath (1925b ; 35, 1926a ; 153-4) is characterised by 

 Anahoplites of the daviesi group. There is virtually no difference in the accompany- 

 ing ammonite fauna in England, but these very characteristic species of Anahoplites 

 have a wide geographical range in this time span, and on this point alone the Subzone 

 should remain separate from that of E. nitidus. Breistroffer's grouping (1965 ; table 

 opp. 312) is not acceptable, and the British reading should be adhered to (e.g. Owen 

 1958 and Hancock 1965 ; 245, 246). 



The Subzone is best developed at Folkestone although it is present in uncondensed 

 sediments elsewhere in Kent and Sussex (Ringmer). However, at Folkestone there 

 are clays representing horizons higher than any known elsewhere outside the U.S.S.R. 

 Even at Folkestone the top of the clays of Bed VII representing this Subzone are 

 planed-off and the basal nodule bed of Bed VIII contains material of late daviesi 

 Subzone age. At Wissant, the lower part of the cristatum Subzone (the partial 

 equivalent of Bed VIII (i) at Folkestone) is represented by clays. Unfortunately these 

 rest non-sequentially upon sediments of nitidus Subzone age (p. 85) and neither at 

 Wissant nor elsewhere in France at this time have sediments of daviesi Subzone age 

 been proved. The development of the Subzone in Russia is mentioned later (p. 132). 



The upper limit of the Subzone can, however, be determined by reference to Bed 12 

 (v) at Wissant which contains no Anahoplites of daviesi type but in which Dipoloceras 

 bouchardianum and Beudanticeras beudanti make their appearance marking the base 

 of the cristatum Subzone. In this bed also there occurs the morphological transition 

 from Inoceramus concentricus to the shell form I. sulcatus (p. 85). 



