24 
The most satisfactory standards of comparison, therefore, are Euro- 
pean strata, and, as has been remarked above, it is among English fossils 
that the most likeness to the Canadian shells has been obtained. Now 
the English deposits which have yielded such like forms give the following 
sequences. 
S.-W. 
Kellaways Rock: 
Kosmoceratids and a 
Macrocephalitid fragment (pr e-opimus 
hemera? 2 
Kellaways Clay: 
Proplanulites and 
Gowericeras (Koenigi, etc., hemerse) 2 
Radiopole Clay with Macrocephalitids (basal 
Kellaways Clay?) 
Combrash Limestone with Macrocephalitids 
in upper part 
N. Yorkshire 1 
Kellaways Rock (lower part) 
Kosmoceratids 
and Proplanulites 8 
Clays of the Combrash 
“Am. macrocephalus ,t 
Combrash Limestone 
“Am. macrocephalus” 
As Macrocephalitids are found occurring in Yorkshire in three and in 
southwest England in four sequential deposits, which differ from each 
other in lithic characters quite materially, the supposition that strata with 
Callovian Macrocephalitoids, which spread over a wide geographical area 
of the globe, represent a deposit of one date, laid down during a great 
submergence, is obviously untenable. And it may be still more untenable 
than it looks from the table of strata given above, for there is reason to 
suppose that these deposits were not only laid down during four hemerse 
but actually occupied several more — perhaps as many as eight — in their 
accumulation. For I have lately suggested that in southwest England 
the Kellaways Clay and the Kellaways Rock represent not merely two 
hemerse but six (1921, p. 40): now evidence seems to indicate that as an 
under-estimate. 
It may be said that at present this is very largely supposition, lacking 
good evidence. This is granted, but there are the following facts in its 
favour: 
(1) The Kellaways Rock of north Yorkshire, though fairly uniform in 
lithic character, was laid down not during one but during many sequent 
hemerse as -its fossil contents show; for much of its fauna is found not in 
Kellaways Rock of southwest England but in several sequent beds of the 
superjacent Oxford clay (1, p. 160): therefore, the Kellaways Rock of the 
southwest need not, because it is fairly homogeneous, represent the deposit 
of only one hemera. 
(2) In Sutherland, Scotland, the Roof Red over the coal is of the date 
of the Kellaways Clay, but, so far as is known at present, it contains some 
of the species of the earliest layer only; this seems to show that what I 
have separated as the two later layers of Kellaways Clay are of later date 
than the Roof Bed. So there is quite a possibility that Macrocephalitids, 
or what would hitherto have been called Macrocephalites, lived during six 
hemerse, if they go no higher than the earliest layer of Kellaways Rock of 
southwest England, or during 7 or 8 if they do go higher. Therefore, 
1 Partly from examination of specimens, partly from information given by Fox-Strangways (VI). 
* Sea S. Buckman, 3, p. 40. 
* The Kellaways Rock of Sooth Cave, Yorkshire, with Kosmoceratids. Catiscephalites, and a form like, but 
not, Proplanulites may be earlier in date. Its fauna differs in detail from the Kellaways Rock of north Yorkshire. 
