118 Mr. J. F. Walker in reply to Mr. Seeley on the 
XVII.—A Reply to Mr. H. G. Seeley’s Remarks on my Account 
of the Phosphatic Deposit at Potton, in Bedfordshire. By 
J. F. Warxer, B.A., F.C.P.S., F.C.S., F.G.S., Sidney Sussex 
College, Cambridge. 
In April 1866 the Rev. P. B. Brodie wrote a paper on the phos- 
phatic deposit near Potton, in Bedfordshire, and stated that the 
fossils were derived from preexisting formations*. Having ob- 
tained from this bed some additional fossils, especially remains 
of Iguanodon, I wrote a short paper, supplementary to Mr. 
Brodie’s, which was published in the Number of this Magazine 
for July 1866. At this period the Woodwardian Museum con- 
tained no fossils from this deposit ; but since then, through the 
exertions of Mr. Keeping, who has the care of the Museum, it has 
obtained a fine series of these fossils. In August of the same year 
Mr. Seeley published a letter criticising the results arrived at 
by Mr. Brodie and myself; but this fact does not appear from 
his reference to that paper in the last Number of the ‘ Annals,’ 
in which he would seem to intend to represent himself as the 
person attacked, instead of the aggressor, in this matter. Mr. 
Seeley stated in his letter that all the fossils appeared to him to 
be “denizens of the old sea-bed where they abound ;” and this 
is the chief point on which our views do not coincide. Mr. Seeley 
says that the only mistake in his paper is the statement that 
“the Gryphea dilatata is perversely wanting.” But I am not 
surprised that Mr. Seeley obtained no specimens of this fossil, 
as the work-people did not save the ferruginous shells until I 
told them to do sot. I will now consider Mr. Seeley’s criticisms 
sertatim. 
I. Mr. Seeley objects to this deposit being called the Lower 
Greensand, and says :—‘‘ The Shanklin (or Lower Green) Sand, 
as I understand it, is the series of beds between the Weald Clay 
and the Gault. But these sands at Potton are between the 
Gault and the Oxford Clay; and, so far as I remember, the 
only fossil previously recorded from the beds in this district is 
Ammonites biplex, mentioned in my paper on the Cretaceous 
beds at Ely,—neither of which facts offers any presumptive 
evidence of the deposit being Shanklin Sands.” Here is his 
statement in the paper he refers to :—‘‘ The lower part of the 
Shanklin Sands is a conglomerate of small rounded pebbles, 
which in the best place in the section is hardly more than four 
feet thick ; and above this are some brown sands alternating 
irregularly with thin courses of clay with phosphatic nodules ; 
* Geological Magazine, vol. i. p. 153. 
+ This circumstance explains Mr. Brodie’s apparently erroneous asser- 
tion that “ every organism in this phosphatic bed is evidently extraneous,” 
which was perfectly true with regard to the fossils obtainable when he wrote. 
