The lower lias of keynsham. 
15 
In the Keynsham district, exposure 12 (Kelston Station;, 
is the only one in which the Psilonotus Beds are completely 
shown. And here, Am. 'planorbis is confined to a single bed 
at the base of the zone, whilst Am. joJinstoni is extremely 
abundant in the limestones above. We ha ve found no specimens 
of Am. johnstoni actually associated with Am. planorbis^ and 
the same statement is true of the section near Kedland, and 
at Stoke Gifford/ where the general faunal succession is almost 
identical with that at Kelston. At Radstock, Am. johnstoni 
is not a common fossil, but, so far as our investigations have 
yet gone, the same sequence holds good here also. At Sod- 
bury,2 Am. planorhis is apparently absent, whilst Am. john- 
stoni is very abundant to the very base of the zone. 
Am. angulatus zone. 
Am. angulatus is a somewhat unsatisfactory zonal index on 
account of its rarity ; even fragments are uncommon, and 
specimens showing the earlier and later whorls in con- 
junction are the rarest finds in the district. As already 
stated, we have never found Am. angulatus associated with 
Am. johnstoni^ either at Keynsham or in the neighbouring 
districts. Owing to the extreme rarity of the zonal index, 
it becomes necessary to select other commoner species as 
sub-zonal indices of at least local value. 
Just above the Psilonotus zone, echinids are so common 
that this horizon may be fittingly termed the Echinid Bed. 
Since only a single, very badly preserved, fragmentary cast of 
an ammonite, whose relationship is extremely donbtfiil, has 
been found in this bed, it is very immaterial whether we 
assign this horizon to the Psilonotus or to the Angulatus 
zone. At Redland, Kelston and Sodburj^ similar Echinid 
Beds occur and, at the two first-mentioned localities, they 
^ ^ Q.J.S.S., vol. Iviii. pp. 727-729. 
2 Q.J.G.S.^ 'Vol. Iviii. p. 719. 
