IN THE ANGLO-PARIS BASIN 117 



Milbourne (1963 ; 58) places the division between the dentatus and lautus Zones 

 above his niobe Subzone (which also includes the subdelamei Subzone of Spath in 

 part) . He finds my Subzone of Euhoplites meandrinus unacceptable and substitutes 

 for it a Subzone of Dimorphopiites dor is and Euhoplites neglechis. He places the 

 subzone in the lautus Zone and so once more the boundary between the two zones is 

 placed at a level where there is no significant change in the ammonite fauna. The 

 differences of opinion between Milbourne and myself led to a skilful review of the 

 zonal scheme by Hancock (1965). Unfortunately two errors were overlooked when 

 preparing Table I of Hancock's paper (1965 ; 245). The eodentatus Subzone was not 

 recognised by me in 1958 but by Casey (1961), and Spath's lautus-nitidus Subzone 

 did not include the time span referred by me to the meandrinus Subzone. The 

 meandrinus Subzone formed part of the subdelaruei Subzone in Spath's sense and it is 

 important to make this point absolutely clear. 



In 1963 a colloquium on the Lower Cretaceous was held in France ; two very 

 important papers being contributed by P. & J. -P. Destombes, and Breistroffer, on 

 the zonal scheme of the Albian. These were published in 1965. P., & J. -P. Des- 

 tombes propose the following arrangement (1965 ; 266). 



Zone Sous-zone Localite-type 



2 — Lyelliceras lyelli et La Vendue-Mignot 



Hoplites benettianus 



LYELLICERATIEN 



1 — Tegoceras camatteanum Cotes Noires de Moeslains 



Isohoplites eodentatus niv. 5 



This proposition is interesting as it shows in the case of Lyelliceras lyelli an 

 independent return to the older view expressed by Barrois, Price, and Kilian, al- 

 though it should be noted that Collignon has also used this index (1963 ; 2). P. & 

 J. -P. Destombes use a hemeral name for the zone. The use of these terms particu- 

 larly by Spath and Breistroffer, is not supported here for they are far too nebulous to 

 have any really precise application. Breistroffer's paper (1965 ; 311 & table) 

 presents an emendation of his zonal scheme of 1947 and he accepts P. & J. -P. 

 Destombes subzonal arrangement for the basal part of the Middle Albian. The 

 scheme given by Collignon (1965b) is quite unacceptable. 



The history of this zonal scheme, like that of any other, has been one of progressive 

 refinement as knowledge of the succession has improved. Unfortunately, the Albian 

 in particular has suffered greatly because of arbitrary decisions concerning the fixing 

 of ammonite zonal and subzonal boundaries. These boundaries have been placed 

 sometimes without sufficient initial research and have been upheld later purely on 

 rather dubious ' historical ' grounds ignoring whether or not there is a significant 

 change in the ammonite fauna. A zonal scheme must remain sufficiently flexible to 

 take account of new discoveries and better developed sequences. To bang in a 

 ' golden stake ' at a convenient level in a so-called permanent type-section might 

 help the theorist but in reality it only hinders progress towards accurate international 

 correlation, and the knowledge of events in the evolution of the Earth that will stem 

 from it. 



