POSITIONS OF THE TRIGONIiE OF NOETH OXFORDSHIEE, ETC. 39 



As far eastward as Chipping Norton and Eawler, in N.W. Oxford- 

 shire, the continuity of the upper beds of the Inferior Oolite of the 

 Cottes^vold type (the Eagstones or Clypeus-grit) is easily traceable. 

 J^orth-eastward of these points, however, so widely different are 

 the conditions of deposit that Mr. Hudleston has well said * : — " The 

 beds of this region have a type of their own, and it is no nse trying 

 to force them into the ready-made clothes of other districts.'' 



The bed (C') at the bottom of the Clypeus-grit (C^) at Pawler, 

 and that at the base of C at Hook jN'orton are similar lithologically, 

 and both contain an abundance of concretionary and derived 

 fragments. Associated with these in each locality are corals of 

 similar species, blocks of limestone covered with oysters and 

 pierced with Litliodomi, numerous shells such as Astarte minima^ 

 Ostrea Marshii, Isocardia, sp., Trigonia producta, T. costata, and 

 T. angidata. With so many features in common, it will be safe to 

 assume the connexion of the seas of these areas with each other at 

 the time of the deposition of the bed, whilst the irregularity of its 

 occurrence at Pawler, where the bed rests, as at the Duckpool-Earm 

 cutting, near Hook I^orton, ujjon the Upper Lias, points also to 

 long and continued erosion in the antecedent period. The classi- 

 fication of these bed^ with the zone of Ammonites ParJcinsoni on 

 the one hand, or the zone of Ammonites Humpliresianus on the 

 other, will depend much upon whether we look to the Cotteswold or 

 to the Dorset types for comparison. The fauna is that of the Lower 

 Trigonia-grit, a division, according to Dr. Wright, of the zone of 

 Ammonites ParJcinsoni, but placed by Mr. Witchell f in the zone of 

 Ammonites Humphresianus. If the remains of the bored bed 

 represent, as seems to be probable, the well-known Upper Preestone 

 bed, then it would point to the destruction of that stratum prior to 

 the formation of the lowest bed of series C. 



The ' Supplementary Monograph on the British Possil Trigonise,' 

 by the late Dr. Lycett, published in 1883 by the Palaeontographical 

 Society, has done much to increase our knowledge of the strati- 

 graphical position as well as of the species of the Oxfordshire 

 Lower Oolites. Some additional information accumulated since the 

 materials were sent to Dr. Lycett in the early part of the year 

 1882 has induced me to proffer these notes to the Society. 



Tm&oisTEA Beodiei, Lye, a pretty little local species, is not un- 

 common in the Lower Inferior Oolite beds A and B\ Its occurrence 

 in any higher stratum is doubtful. It is nearly allied to T. formosa, 

 Lye, of which it may possibly be a local development. The pro- 

 minent distinguishing feature between the two species consists in 

 the more vertical position of the lower costse of T. formosa. The 

 beds A and B seem to represent the zones of Am. jurenms and 

 Am. MurcMsonce. 



* " Eeport of the Excursion of the Geologists' Association to Chipping 

 Norton," by W. H. Hudleston, M.A. (Proc. G-eol. Assoc, vol. v. no. 7, p. 9). 

 t 'Geology of Stroud,' by E. Witchell, F.G.S., p. 57. Stroud : 1882. 



