Arkell.1956.Jurassic..

-26 THE BRITISH ISLES
•of K. grossouvrei Douville and a lower subzone of K. obductum
{Buckman).
Zone of Kosmoceras jason (Reinecke). The lowest 2-5 m. of the Oxford
Clay shales are characterized from Dorset to Peterborough by Kosmoceras
(Gulielmites) jason and its allies (including K. conlaxatum). In these
beds at Peterborough occur Kosmoceras gulielmi (Sow.) and Reineckeia
rehmanni (Oppel).
LOWER CALLOVIAN (Kellaways Beds, 8-20 m., and Upper Cornbrash,
0-7-8 m.)
Zone of Sigaloceras calloviense (Sowerby). The zonal index (proposed
by Oppel for the Kellaways Rock) occurs only in Wiltshire and perhaps
adjacent counties, not in Yorkshire (contrary to some published statements).
The Kellaways Rock of South Cave, Yorkshire (inland) belongs
to a higher horizon, which Callomon (1955) regards as a separate subzone
of Catasigaloceras planicerclus Buckman. It is characterized by great
numbers of this species and its varieties or allied species, with Kosmoceras
aff. gulielmi (Sow.), Pseudocadoceras cf. grewingki (Pompeckj), Cadoceras
sublaeve (Sow.), C. durum (Buck.), C. milascheviki (Nikitin), C. tchefkini
(d'Orb.), Proplanulites spp., Chqffatia difficilis (Buckman), etc.
The Kellaways Rock of Wiltshire, subzone of Sigaloceras calloviense,
likewise contains many Cadoceras spp. and Proplanulites spp., together
with Kepplerites spp., especially the gowerianus group, but no Catasigaloceras.
The type-locality for Kepplerites gowerianus (Sow.) is the
Brora Roof Bed in east Scotland. This fauna is well represented on the
Yorkshire coast in the Kellaways Rock.
The Kellaways Clay, under the Rock, in the south of England consists
of two parts belonging to different zones. The typical fauna in the
type area, Wiltshire, belongs to the upper part and is the same as that
found in Rock facies in Oxfordshire, Yorkshire and Kent (Callomon,
1955). Owing chiefly to the different preservation in Wiltshire, Buckman
(1913) introduced for this fauna a separate zone of Proplanulites
koenigi (Sow.), but Callomon has shown that there is no noteworthy
difference from the fauna of the Wiltshire Kellaways Rock and he
considers that the Koenigi Zone is at most a subzone of the Calloviense
Zone.
Zone of Macrocephalites macrocephalus (Schloth.) (=M. verus Buckman;
see pi. 37, fig. 6).
An upper subzone of Macrocephalites kamptus (Buckman) is adopted
by Callomon from Buckman for the Upper Cornbrash of Yorkshire,
which was already considered later than the southern Cornbrash by
Lycett (1877, Mon. Brit. Foss. Trigoniae, Pal. Soc, p. 172). Its
ammonites comprise an assemblage of Macrocephalites s.s., Dolikephalites
and, above all, Kamptokephalites (herveyi-kamptus group). The same
forms are found in Upper Cornbrash at least as far south as Peterborough
and Bedford, but already in this area the subzone begins to be replaced
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