300 
HUGHES : INGLEBOROTJGH. 
There is at the present time a " boom " on zoning, and 
excellent work has been done upon it, but the value of tlie results 
depends upon how nearly the observers have exhausted the 
evidence. To assert that any form " a " does not occur at the 
same horizon as another form " d " is only to say that the ob- 
server has not yet found it there ; and, when we remember 
that, in the sections of which I am speaking, very few could 
find the Lower Zone of even such a large conspicuous fossil as 
P. gigantea in the stream below the Shooting Box, and that, 
if the weather is bad, not even one who knows every inch of 
the ground could be sure of showing you that species in situ in 
the Upper Zone on Simon Fell, we may well be cautious about 
basing important generalisations on negative evidence. 
The next stage will be a " boom " on nnzoning, that is upon 
proving the greater continuity of life than has been supposed 
in certain areas, with remigrations into adjoining areas as con- 
ditions again become suitable for any particular species, unless 
in the interval that species has become extinct. Palaeonto- 
logists are much inclined to exaggerate the importance of in- 
dividual variations, especially when looking over collections 
made for them, and they have not themselv^es had opportunities 
of studying the variations on the field, and the variation has 
not been uniformly impressed upon a sufficiently large number 
of individuals to constitute what is technically known as a 
variety. 
The Top of Ingleborough. 
The Main Limestone is succeeded by shale, which is no- 
where seen in a clear section where its thickness could be exactly 
measured or its character observed. It is probably over 120 feet 
in thickness and seems, from fragments lying about, to contain 
some bands of flaggy sandstone. It is seen resting on the lime- 
stone at the Arks on the north side of the summit, and crops 
out a short way below the sandstone on the south side. Frag- 
ments of shale occur also in a similar position below the north- 
west corner. A small excavation would clear up these points 
and give an opportunity of looking for fossils in the calcareous 
