R. M. Brydone — Stages of the Upper Chalk. 57 



stages in the middle of the old zone of Actinocamax quadratus. The 

 reception to be given to this proposal so far as it concerns France and 

 Germany must be a matter for the geologists of those countries, and 

 I am concerning myself chiefly with the proposal as it affects the 

 English Chalk. Inasmuch as I sympathize with the proposal, and 

 my own work is partly relied upon, it may seem ungracious in me tO' 

 criticize it, but there are several points on which criticism seems 

 desirable if only to afford Mr. Jukes-Browne an opportunity of 

 replying while the subject is still fresh. 



In the first place, he appears to intend at the top of p. 306 to 

 endorse a proposal by me to constitute a new zone, the zone of Offaster 

 pilula, for the reception of the lower two out of the three subzones 

 into which Mr. Griffith and I divided the old zone of A. quadratus. 

 It is, however, not very clear that this is so, and any uncertainty 

 is rather unfortunate, as when he wrote my proposal was still 

 unpublished, being taken by him from letters in which I told him 

 that I was about to publish such a proposal and gave my main new 

 grounds in order to obtain his opinion as to the permissibility of 

 a subsidiary proposal. It was, perhaps, inevitable if he could not 

 wait for the publication of my proposal — now happily accomplished^ 

 — that he should quote from these letters; but it seems hardly fair that 

 in doing so he should ignore the new grounds on which the proposal 

 was based, or that he should write on p. 369 that the line at the top of 

 the zone of 0. pilula had not yet been accurately determined in England 

 when the letters from which he apparentlj^ drew the main proposal 

 of a zone of 0. pilula in England showed that this line had been 

 accurately determined in South England, to which my proposal was 

 limited. 



In the second place, in his list of zones on p. 308 the zone above 

 that of Marsupites appears as the " zone of Offaster pilula^\ At the 

 foot of p. 310 it appears without warning as the " zone of Actinocamax 

 granulatus ". In Table II it appears again without waining as the 

 " zone of Offaster pilula and Actinocamax granulatus ". In Table III 

 it again changes to " zone of Offaster pilula^\ in Tables V and VI to 

 "zone of Offaster pilula and Actinocamax granulatus^', in Table VII 

 to " zone of Offaster pilula''' , and finally in Table IX to "zone of 

 Offaster pilula and Actinocamax granulatus" . These apparently arbitrary 

 intrusions of A. gratiulatus, when read with the statement next but 

 one to be criticized, leave me practically certain that Mr. Jukes-Browne 

 intended, at any rate during part of the time he was writing, to lay it 

 down that the ranges of A. granulatus (upwards from the Marsupites 

 zone) and A. quadratus (below the Belemnitella miicronata zone) 

 corresponded with the two divisions of the old zone of ^. quadratus on 

 which he was working. 



I am afraid that on this point he may have fallen into a trap which 

 I certainly laid for him, tliough quite unwittingly. In " The Zones of 

 the Chalk in Hants ", A. gratttdatus appears as having occurred in four 

 of the collated pits in the suhzone of 0. pilula (which is the upper 

 part of the new zone of 0. pihila). All the specimens in question 



' See The Stratigraphy of the Chalk of Hants. London, Dulau & Co. , Ltd. ,1912. 



