A. J. Jukes-Browne — Zones of Loiver Chalk. 509 



Totternhoe Stone has much more affinity with the beds above than 

 with the beds below. 



I record this result as an answer to Mr. Bosworth's peculiar mode 

 of dealing with the matter, but I do not wish to lay much stress on 

 the argument, for I regard mere percentages as deceptive and 

 unsatisfactory tests, unless the abundance of characteristic species 

 is taken into account. I am quite disposed to give due weight to 

 the fact that Schloenbnchia varians, Scaphiles cequahs, and several 

 species of Turrilites, which are important members of the southern 

 Chalk Marl fauna, occur also in the Totternhoe Stone. Indeed, 

 I regard this stone as a band of rock developed at the junction of 

 the two zones at a time when some species were dying out and 

 when others were coming in, so that it might with equally good 

 reason be placed in either zone. 



I have stated the reasons which originally induced me to regard 

 it as the base of the higher zone, and I do not see that any clearer 

 idea of its real position as a passage bed would be gained by trans- 

 ferring it to the zone of Ammonites varians. My own feeling is that 

 the matter had best be left where it stands until a larger body of 

 evidence has been obtained. 



1 have next to deal with Mr, Bosworth's statements regarding the 

 recorded occurrences of Hohister subglohosus and H. trecensis, some 

 of which are certainly incorrect, while others require confirmation. 



He states that H. subglohosus is nearly as common in the zone 

 of A. varians as in the beds above throughout Hampshire, Wiltshire, 

 Isle of Wight, Sussex, and Kent ! So far as I know this is only 

 true of the Isle of Wight, and the rest of the statement absolutely 

 contradicts that made by me in the General Memoir above mentioned 

 (vol. ii, p. 17). It IS true that Mantell recorded H. subglohosus from 

 Middleham, Maddock found it in the Chalk Marl of Eastbourne, and 

 Etheridge in that of Folkestone, but so far as I know these records 

 have not been oonfirmed by later collectors. On the other hand, 

 this urchin is a common fossil in the central part of the Lower 

 Chalk throughout Kent and Surrey, as well as at Lewes and 

 Eastbourne in Sussex. If Mr. Bosworth has any special information 

 about the distribution of this fossil in the counties mentioned he 

 should publish it. 



Again, I am obliged to contradict bis statement that H. subglohosus 

 is a rare fossil above the Totternhoe Stone in Lincolnshire and 

 Yorkshire. Such an idea can only be due to careless reading of the 

 records and descriptions given by Mr. W. Hill and myself. In the 

 General Memoir (vol. ii, p. 20) I wrote: " ITolaster subglohosus is 

 not uncommon in these beds both in Yorkshire and Lincolnshire, 

 but it is equally common in the zone oi Am. varians, so that it will be 

 more convenient to take Offaster sphcericus as the index of the zone 

 in these counties." 



With respect to IT. trecensis I shall be glad to know on what 

 authority Mr. Bosworth asserts that in Dorset and Devon this 

 species " is plentiful in the beds above the A. varians zone, . . . 

 is almost confined to the zone and could well be used as the zone 



