256 



ME. T. EOBEETS ON THE TTPPEE JTTEASSIC EOCKS 



that is to say, they are pyritized. This sub-stage includes the zones of 

 Amm. biarmatus, A. athleta, and A. anceps of Oppel, who correlates 

 it with the Oxford Clay of S.W. England, and with the Oxford Clay 

 and part of the Kelloway Rock of Yorkshire. Waagen and Renevier 

 similarly place it on the horizon of the Oxford Clay. 



In Yorkshire, Hudleston (op. cit.) makes a three-fold division of 

 the Oxford Clays : — 



3. Upper, with Amm. perarmatus, rarely. 

 2. Middle, with Amm. Eugenii, A. crenatus, &c. 

 1. Lower, with. Bel. Owenii, Ammonites Lamberti, A. athleta, A. oculatus, 

 and A. crenatus. 



Further south, in Northamptonshire and Bedfordshire, where 

 there is but a thin development of the Kelloway Rock, the following 

 subdivisions have been made out by Prof. Judd (" Geology of Rutland," 

 Mem. Geol. Surv. p. 232) :— 



ornati and Terebratula 



f. Clays with cordati group of Ammonites. 

 e. ,, „ Ammonites of the group 



impressa. 

 d. Clays with Belemnites hastatus. 



c. „ „ Owenii. 



b. „ ,, Nucula nuda. 

 a. Kelloway Sands, &c. 



In the south-west of England the two zones, an upper with 

 cordati and a lower with ornati Ammonites, have also been recog- 

 nized (H. B. "Woodward, Q. J. G. S. vol. xlii. p. 295). 



The list of fossils from the ' Fer sous-oxfordien ' of the Jura Bernois 

 given by Greppin (op. cit. p. 58) contains 86 species, 26 of which 

 occur in England at the following horizons respectively : — 



19 species in Oxford Clay. 

 4 „ Lower Calcareous Grit. 



1 „ Corallian. 



2 „ range from Oxford Clay to Lower Calcareous Grit. 



The following fossils, amongst others, are common to the Oxford 

 Clay and the ' Fer sous-oxfordien ' : — 



Belemnites Puzosianus, IP Orb. 

 Ammonites crenatus, Brug. 



Lamberti, Sow. 



Maria?, If Orb. 



cordatus, Sow. 



oculatus, Phil. 



Ammonites athleta, Phil. 



Henrici, D' Orb. 



perarmatus, Sow. 



Leda (Nucula) lachryma, Sow. 

 Terebratula impressa, v. Buch. 



It will be seen therefore that both the cordati and ornati Ammo- 

 nites are well represented. In England Amm. perarmatus is found 

 principally in the upper part of the Oxford Clay, but more commonly 

 in the Lower Calcareous Grit ; in the Jura it occurs in the Oxfordian 

 as well as in the ' Fer sous-oxfordien,' and this would indicate a high 

 position in the Oxford Clay for the ' Fer sous-oxfordien.' Gryphceq 

 dilatata, our most common Upper-Oxford-Clay fossil, is, on the 



