Amn. 
communis. 
A Vivi. 
serpentinus. 
Amm. 
spinatus, 
270 MR. E, A. WALFORD ON [May 1902, 
there is at the top of the Middle Lias of the Northamptonshire 
border a paleontological gap perhaps better defined than any other 
in the Lower Jurassic Period. It is shown in the stratum of marl 
that I have called the Transition-Bed of the Middle Lias, and the 
section of Fernhill near Banbury, on the Great Central Railway, is 
one, from its completeness, best suited for ‘illustration. Other 
sections that I described twenty years ago are at Chipping Warden 
and Byfield, a few miles north-west of Fernhill. 
FERNHILL, 
C.CR. FERNHILL KING’S 
(Aqueduct aie Onaek BLoxHAM. FAWLER, 
cutting, N.b ie I S oe ) 
S. bank.) (N. bank.) Ironworks. 
Ft. In. Ht. in: Pts dn: Et. in: Ft. 
1. Humus and waste ............... 2 0 6 0 2 4 2 0 2 
2), IBilney (Oli Saaessrsoseanonpce sooarosor 8 0 ) eee) ALM eee 15 0 16 
3. Pentacrinite-limestone ......... 1 16 0 
4. Clay, with line of ferruginous ( 
THO) 01 (2 Mere ROP AAR abe sce SERACHBE 2 OU A A Panser tice 2 0 
5. Limestone with Am. bifrons... 1 a) 10 Dis. ap eee 
6. Clay, with small ammonites 
and belemnites ............... 4 0 7 6 
7. Limestone, with small ammo- 3 6 
nites and belemnites......... 5 6 
AA (CLER  Agenbconachos0d BodosaErpnonHnee 3 0 3 0 
9, Blue Limestone (sharp frac- 
ture) with Am. Strangwaysii 9 8 
10; Raper-shallesi....i!...022.020s02- 6 5 
11. Purple and black limestone 
(fish-bed) with Amm.Strang- 
waysit, communis, etc. ....++ 4 2 a trace 
12. Calcite-veined limestone ... T is 
13. Grey argillaceous mar] ...... eae Baie ) cacdss a trace 
14. Red-brown mar] ............... eae“ s 4 + 
15. Marlstone—zone of Amm. ‘ 
SAU TY Cb) kenerespcpacsba reno) eecagn eh  easdar 5 0 20 0 11 
In part welded with the upper part of the Middle Liassic rock- 
bed, and in part resting upon it, is a stratum of fawn-coloured marly 
limestone weathering to marl, varying from 3 to 6 inches in thickness. 
It brings in a large assemblage of life-forms, and attains greater 
importance owing to the Ammonitidz being so abundantly developed 
therein. Tate & Beesley * noticed the occurrence of the fauna at 
Adderbury, but it is not there distinguished as a separate horizon. 
In Northamptonshire, where better conditions prevail, I collected and 
tabulated from the several localities 175 species of mollusca: now 
the number is considerably greater. 
No period of geological life is better marked than the time of the 
incoming of Ammonites communis and its allies in the Lias. 
Throughout the whole of England, and also throughout the whole 
of the Anglo-Norman area, there had been a long pause in conditions 
favourable to the growth. of the Ammonitide. The Spinati almost 
died out at the base of the great Ironstone Series of the Midlands, 
and it was apparently the same elsewhere. They occur but rarely 
in the ironstone of the Ferrocrinoid time. Early forms of the 
1 Thomas Beesley, Rep. of Excurs. to Banbury, Proc. Geol. Assce. vol. iii 
(1873) p. 197. if 
4 ea 
eG 8 
