362 A. J. Juices Browne — On the Upper Greensand, etc. 
either indigenousor derivative ; it has on this account beeil generativ 
confused witli the sands below, and the two together have been 
called Chloritic Marl. Dr. Barrois, however, has skown that it is 
divisible from these sands in Hampshire, and it seems probable that 
the latter are lenticular beds belonging to the P. asper zone some- 
times attaining a thickness of 10 or 15 feet and sometimes thinning 
out altogetker, while the thin bed of sandy marl with glaueonitic 
and phosphate nodules has a wider extent, and is probably to be 
found at the base of the Chalk-marl all round the Weald ; its exist- 
ence is very marked in the neighbourhood of Maidstone, where it 
directly overlies the Gault, as at Cambridge, witkout the interposition 
of any Upper Greensand strata whatever. 
The thickness of this bed is rarely more than 3 or 4 feet, but 
it passes gradually upwards into the Chalk-marl from which it is 
inseparable, except so far as its green grains and phosphate nodules 
give it a character of its own. Thus it is clear that the narrow zone 
of glaueonitic marl lying at the base of the Chalk cannot be con- 
sidered as forming a separate division, and therefore does not merit 
such a name as that of Chloritic Marl, which at once suggests a 
comparison with the Chalk-marl, and gives it an importance far 
greater than it possesses ; moreover, it has often been pointed out 
that the name itself is based on a miseonception, in as much as the 
green grains are not composed of Chlorite but Glauconite, and I 
therefore agree with Mr. Wkitaker and Mr. Price in advocating the 
entire abandonment of the name. 
Since, however, the bed itself does exist as a zone subordinate to 
the Chalk Marl, it is desirable that some name indicative of this 
should be assigned to it ; Mr. Davidson and Mr. De Rance have 
called it the zone of Scaphites cequalis, and perhaps that name can be 
adopted ; at the same time it may be observed that this fossil is both 
of wide and partial distribution ; it is known to occur both in the 
beds above and below, while in some areas, as at Cambridge, it 
does not seem to exist in the zone of which it is supposed to be 
characteristic. It may therefore be found more convenient to indi- 
cate this horizon by one of the numerous sponges, which it every- 
where contains, and which are now being described by my friend 
Mr. W. J. Sollas. Or, lastly, it may have to be ainalgamated with 
the horizon immediately succeeding it, which Dr. Barrois calls the 
zone of Plocoscyphia meeandroides, further Information being required 
concerning the persistence of this band and its relation to the marl 
below. 
Finally, it is desirable that some more clear definition of the 
Upper Greensand should be given. I remember Prof. Ramsay once 
observing that Gault and Greensand were the same thing, and 
doubtless they are in the sense that no hard and fast stratigraphical 
line can be drawn between thein, but taken as a whole it is found 
that the series can be divided into three groups of beds, each con- 
taining a peculiar fauna of its own, and worthy of a separate name. 
Dr. Barrois says that the English Upper Greensand consists of two 
parts, which he calls the zones of Am. inßatus and Pecten asper, but 
