Arkell.1956.Jurassic..

322 EAST AFRICA
Posidonia alpina (= ornati) occurs in some localities with Callovian
(loc. 18) and even higher ammonites (loc. 25), as well as in the Middle
Bajocian.
Large collections have been received while this book was in the press,
and only brief mention of some of them can be inserted in proof. For
correlation see Table 16, pp. 310-11.
MIDDLE KIMERIDGIAN (Beckeri Zone)
From the eastern slopes of Coroa Mombasa, Spath (1930, p. 63, 1933,
p. 818) records Phylloceras aff. saxonicum Neumayr, Taramelliceras cf.
kachhense (Waagen), Lithacoceras sp., Katroliceras sp., Subdichotomoceras
sp., Pachysphinctes major Spath, P. habyensis Spath, Aspidoceras
wynnei (Waagen), Hybonoticeras aff. hybonotum (Oppel) and H. sp. nov.
'This is clearly a Middle Kimeridgian assemblage, referable to the Beckeri
Zone', and it is the highest Jurassic assemblage yet obtained from Kenya.
To the list should be added Katroliceras pottingeri (Sow.), figured by
Futterer (1894, pi. i) and Spath (1931, Cutch, pi. cii, figs. 5 a-d) as identical
with the Cutch species, and Hybonoticeras hildebrandti (Beyrich) figured
by Futterer (1894, pi. iii).
LOWER KIMERIDGIAN
To the Lower Kimeridgian belong many Changamwe Shale ammonites,
especially the common Perisphinctes (Torquatisphinctes) beyrichi Futterer
(1894, pi. ii) and many Aspidoceratids such as A. iphicerum (Oppel),
A. iphiceroides Waagen, A. aff. longispinum (Sow.), A. kilindianum Dacque
and Physodoceras liparum (Oppel), also Holcophylloceras polyolcum
(Benecke) and abundant Belemnopsis tanganensis (Futterer). The D'Arcy
Exploration Company collected most of these at Mtwapa Creek, north of
Mombasa, and with them were Taramelliceras cf. kachhense (Waagen)
and Perisphinctes cf. mombassanum Dacque.
UPPER OXFORDIAN
Bimammatum Zone. To this zone probably belong most of the Perisphinctids
figured from the Mombasa area by Dacque (1910) and placed
by him in the Upper Oxfordian but subsequently stated by Spath to be
Kimeridgian: namely, P. (Discosphinctes) fraasi Dacque, P. (D.) mombassanum
Dacque at least in part, P. (Dichotomosphinctes) krapfi Dacque,
and P. (D) inconstans Spath, 1925 (=- P. virguloides Dacque, 1910, pi. iii,
fig. 1, non Waagen); also P. (Dichotomoceras) anomalum Spath (1930,
p. 45, pi. vi, fig. 1), which is close to P. (D.) dichotomoides Arkell of the
English Pseudocordata Zone and doubtless contemporary with the
Ringsteadiae figured by Scott from Abyssinia (see p. 316). To this zone
belong several Taramelliceras recorded by Spath and a Perisphinctes
(Orthosphinctes) aff. tiziani (Oppel) collected by Mr Caswell at Tangila.
Transversarium Zone. An interesting assemblage of this zone, well
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