28o The Zones of the Lower Chalk. 



This is coniirmed by Dr. Rowe who, writing of the chalk exposed in the 

 clii?s near ' Kit Pape's Spot ' (Flamborough Head), says* — 



" Below the hoi'izontal tissure is the zone of Holaster subglobosus. 

 ... It would seem a hopeless quest to attempt to get fossils from 

 such a matrix, but we had the good fortune to obtain two undoubted 

 examples of Holaster subglobosus from it, and thus to place the horizon 

 of this chalk beyond any possibility of doubt. ' 

 It is clear from the context that the beds referred to are those imme- 

 diately underlying the Actinocamax planus marls. 



Nor is the i:se of Holaster trecensis as a name fossil for the upper zone 

 any more satisfactory, for in Sussex, the Isle of Wight, and in Dorset this 

 fossil is foimd as far down as the lower part of the Chalk Marl. 



Messrs. Bower and Farmery speak of a ' scheme which recognises domi- 

 nant forms as the guides to zonal terminology.' But it is difhcult to see 

 how this description applies to their own proposals ; for, as we have already 

 pointed out, in many parts of England, Holaster subglobosus, so far from 

 being the ' dominant fornr ' in the beds below the Totternhoe Stone, is 

 often entirely absent. In fact, it is impossible to find any fossil which can 

 be used with absolute satisfaction, and without local exception, as an index 

 species for the highest part of the Lower Chalk, but it certainly is not an 

 improvement to make the peculiar zonal distribution of species in the 

 Lincolnshire Chalk the basis of a general system of zoning. In fact, the 

 .authors of the paper seem quite prepared when it suits their purpose to 

 treat the Lincolnshire fauna as of slight importance for they say (page 338) : 

 ' Holaster subglobosus does not occur in the upper beds of the zone 

 to which the name of the echinoderm has been applied, with certain 

 not very weighty exceptions — the Isle of Wight, and Lincolnshire and 

 Yorkshire.' (The italics are mine). 

 They seem to forget that zonal nomenclature adopted by Mr. Jukes- 

 Browne in his memoir on the Lower and Middle Chalk, was intended to 

 apply to the whole of England, and that being based upon the general 

 distribution of fossils throughout the Chalk areas generally, very strong 

 reasons must be given before any district should be excepted from its 

 application. There is really no reason why Ammonites varians should 

 not be employed as the index of the lower zone in Lincolnshire and York- 

 shire, as in all the other parts of England. True it is not so abundant in 

 the two counties mentioned as it is elsewhere, but then for some reason all 

 Cephalopoda are more rare in Yorkshire and Lincolnshire than they are 

 in the South of England. Still it does occur, and it is a species which has 

 never been found for certain above the Totternhoe Stone in any part of 

 England. 



Messrs. Bower and Farmery seem to be unaware that this very question 

 was discussed by Mr. Jukes-Browne so recently as 1906 (' Geological 

 Magazine,' 1906, p. 510) apropos of Mr. Bosworth's suggestion to call the 

 upper zone by the name of the ' Two Holaster s zone.' He then remarked 

 that Haploceras austeni may eventually prove to be a better index, although 

 it is not so common and has once been found in the zone of Ammonites 

 ■varians. 



As regards the central part of the Lower Chalk, the evidence for the 

 new sub-zone docs not strike us as being particularly strong. The name 

 fossil, Terebratulina oriiata, has not been previously recorded in this country, 

 and I am informed by Mr. Jukes-Browne that it is probably identical with 

 Terebratulina nodulosa Eth. This latter fossil is quite common in the 

 Totternhoe Stone, so if it be the same as the Terebratulina recorded froin 

 the Lower Pink Band, it is of no value as a zonal index for the latter bed. 

 The authors of the paper do not give any information which would enable 

 us to determine its identity. Another reason assigned for regarding these 



* ' Proceedings of the Geologists' Association,' Vol. XVHL, part 4, 

 page 201. ' The White Chalk of the English Coast — Yorkshire.' 



Naturalist, 



A 



