Arkell.1956.Jurassic..

472 BALTIC REGION AND POLAND
Dichotomosphinctes spp. (pi. iv, fig. i, pi. iii, fig. 2) and an Arisphinctesnucleus
(pi. iii, fig. 8) all indicate the Plicatilis Zone.
On the other hand a minority of Boden's figures show forms which, by
themselves, would indicate an earlier date (Cordatum Zone): the Properisphinctes
(pi. iii, figs. 4, 5), Prososphinctes (pi. iii, figs. 6, 7) and a single
fragment of Cardioceras costicardia Buckman (pi. i, fig. 16). Possibly
the explanation is that the material was derived from museums, not
collected in situ. This should not at this stage be assumed, however.
Beneath these irony ammonite beds are 7 m. of black, sandy, micaceous
clay with some of the same ammonites in the upper half (Brinkmann,
1927, p. 57) and, in the middle, two layers of septaria which contain nests
of ironshot oolite with abundant Cardioceras (Plasmatoceras) tenuicostatum
Nik. and C. (P.) popilaniense Boden. These small, very finely ribbed
Cardioceratids occur in similar concentration at the base of the Plicatilis
Zone at Heersum near Hanover and in the Arngrove Stone near Oxford.
Extreme difficulty of specific determination, however, detracts from their
value for wide correlation (Arkell, 1941, Mon. Am. Engl. Corallian Beds,
p. 230). With them at Popilani occurs Euaspidoceras perarmatum Sow.
sp. (Pakuckas, 1933, p. 478). Haldager boring in Denmark yielded
Trigonia hudlestoni Lycett, of the early-Upper Oxfordian, in a series of
clays and claystones.
LOWER OXFORDIAN
Some ammonites which seem to belong to the upper part of the Lower
Oxfordian are figured by Boden with the Plicatilis Zone assemblage, as
mentioned above. According to Brinkmann's profile (1927, p. 57) there is
no other likely bed for these to have come from; for the 3 m. of sandy
black micaceous clay under the Cardioceras tenuicostatum nodules rests
directly on the Lamberti Bed, with Kosmoceras. Similarly Krenkel
(1915) figured a few ammonites which could belong to the lower part of
the Lower Oxfordian among the Callovian fauna: namely }Pavloviceras
sp. (pi. xxii, figs. 21-24) and a Cardioceras (Scarburgiceras) sp. (pi. xxii,
fig. 14). Peltoceras arduennense (d'Orb.) is recorded from borings at
Hohensalza and Heilsberg, and from the Pomeranian drift.
UPPER AND MIDDLE CALLOVIAN
In the banks of the Windau at Popilani the Middle and Upper Callovian,
comprising the Coronatum, Athleta and Lamberti Zones, is condensed
into 7-65 m. of strata, consisting mainly of sandstones and sand. Wellpreserved
ammonites occur at a number of horizons and have been
monographed by Siemiradzki (1890, 1890a), Krenkel (1915) and Pakuckas
(1932, 1933). The stratigraphy and the Kosmoceratids have been revised
by Brinkmann (1927, 1929).
At the top is the Lamberti Zone, a bed 0-15 m. thick, containing
abundant Quenstedtoceras henrici Douville (Krenkel, 1915, pi. xxii, figs.
16-20) (but not, apparently, Q. lamberti) and rare Kosmoceras cf. spinosum
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