Oxford and Ampthill Clays. 397 
survived. ‘his is the case not only in England but in Normandy,' 
and perhaps in South Germany (to judge from some of Quenstedt’s 
figures). 
Mr. Buckman has distinguished a lamberti zone below the renggert 
zone,” but the evidence on this head is unsatisfactory. There were 
in the Ludgershall cutting two bands of soft earthy limestone, one 
highly fossiliferous, the other not. ‘he former contained large 
specimens of Quenstedticeras sutherlandie (d Orbigny) and Peltoceras 
spp. The air-chambers of these fossils are filled with rock-matrix, 
and the casts are sometimes overgrown with serpule and bryozoa, 
and have been subject to wear and tear subsequent to this encrustation. 
They certainly indicate a different fauna from that of the renggeri 
clays, but I collected the renggeri fauna from below as well as 
above the stone-beds, although as the collecting was made on 
a sloped surface the fossils may have come from above. At Woburn 
Sands two exactly similar beds (called elunch by the workmen) are 
found, and here I am quite sure that the renggerd fauna occurs 
in situ below as well as above the clunch. The fossils in the clunch, 
however, are not the same as at Ludgershall. Thus there are several 
puzzles to be cleared up before we can decide whether the differences 
of fauna indicate difference of age or difference of conditions. 
6 and 7. Vhe pre-cordatum zone.— This term was used by 
Mr. Buckman® as a provisional name for the uppermost beds of the 
Oxford Clay, containing ammonites in some respects intermediate in , 
character between Quenstedticeras and Cardioceras, having ribs with 
less geniculation, less tuberculation at the peripheral margin, and less 
of a forward sweep on the periphery than in the latter genus. Such 
are Nikitin’s species,* rotundatus, rowillert, vertebralis, tenurcostatus, 
quadratoides, Lahusen’s nikitinianum, and possibly his cordatum and 
excovatum in part, and de Loriol’s*® C. cordatum vars. B to F (perhaps 
var. A also). 
More recently Mr. Buckman has used the term ‘‘ scarburgense 
zone”’ in place of ‘‘pre-cordatum zone’’.6 There seem, however, to 
be at least two zones distinguished by ammonites of this general type. 
In the lower there are fairly stout species of the quadratoides type, 
preserved as pyritic casts; in the higher, thinner forms with finer 
ribbing (tenwicostatum type) occur with shell preserved. Both zones 
contain large examples of Gryphea dilatata, auctt. 
The lower pre-cordatum zone was exposed in ditches on the low 
ground between Woodperry and Studley, at the brick-field south-east 
of Studley, in the Great Central railway cutting north of Wotton 
station, and at the brickfield close to Quainton Road junction. 
How far it may correspond to any of Mr. Buckman’s Yorkshire zones 
1 Z.. Brasil, Bull. Soc. Géol. Normandie, xvii, pp. 36-49, 1896. 
2 §. S. Buckman, op. cit., p. 159. 
3 In Lamplugh & Kitchin; Mesozoic Rocks in Coal Explorations in Kent 
(Mem. Geol. Surv.), 1911, p. 132. 
4 S.N. Nikitin, Jura Ablagerungen zwischen Rybinsk, Mologa und Myschkin 
an der oberen Wolga (Mém. Acad. Sci. St. Petersburg, xxviii, 1881). 
> Op. cit., xxv, pp. 14-22. 
§ Q.J.G.S., lxix, pp. 157, 159, 1913, and in Geology of . . . Whitby and 
Scarborough (Mem. Geol. Sury.), 1915, pp. 60, 87. 
