E. A. WALFORD 02T THE TEIGOI^LEE OP X. OXFOEDSHIEE, ETC. 35 



7. On the Stratigeaphical Positions of tlie Teigoni^: of the Lowee 

 and Middle Jueassic Beds of j^oeth Oxfoedshiee and adjacent 

 DisTEiCTs. By Edwiit A. Walfoed, Esq., F.G.S. (Read 

 jN"ovember 19, 1884.) 



[Plate I.] 



A WELL-defined family of the Mollusca making its appearance and 

 attaining its maximum development within a limited geologic 

 period must necessarily be of exceptional interest to the palseonto- 

 logist. Such a family, the Trigoniae, though from their irregular 

 dispersion and less vagrant habit inferior to the Ammonites as 

 stratigraphical guides, supply nevertheless no unimportant evidence 

 thereon, finding, as they do, a birthplace in the lower beds of 

 the Lias, and in the Inferior Oolite leaping into such numerical 

 luxuriance that Dr. Lycett has well described it as " a very metro- 

 polis of the Trigoniae." Though fairly represented in the higher 

 Jurassic series, yet with gradually diminishing importance notwith- 

 standing a brief JN'eocomian revival, they range through the j\Ieso- 

 zoic period, and now in Australasian seas linger as the remnant of 

 a once dominant race. 



In wealth of individual forms as weU as in number of species the 

 narrow Jurassic area of Iforth Oxfordshire stands prominent. As 

 elsewhere, the Lias species are few. 



LiAssic Species. 



Teigonia LESTGONEi^sis, Dumort. — In the zone oi Ammonites Henleyi 

 of the Middle Lias of Banbury a doubtful cast of this species has been 

 found. I have recorded it also from the zone of Ammonites spinatus * 

 at Kings Sutton and Aston-le-Wall, localities on the borders of jS'orth- 

 amptonshire. At Preston Capes, in Northamptonshire also, it has 

 been collected by Miss Baker f. 



Teigoxia noethamptoi^ensis, nov. sp. (PI. I. figs. 4-7.) 

 The few immature forms of this species which had come under 

 my notice until quite recently caused me to refer them with some 

 degree of hesitancy to the Yorkshire shell T. literata, T. & B. The 

 adoption of a new name has seemed necessary under the additional 

 light thrown by the acquisition of a better-developed series of 

 examples and by an expression of opinion from a palaeontologist 

 of wider experience than myself. Though perhaps the differences 

 between the two forms may to some extent be due to regional varia- 

 tion, yet we have to remember that in the course of the Lias from 

 Yorkshire through Lincolnshire and Leicestershire, no connecting 

 link seems to have been met with. 



* " On some Middle and Upper Lias Beds in the Neighbourhood of Ban- 

 bury," by E. A. Walford (Proc. Warwicksh. IVat. & Arch. Field Club, 1878). 



t "On the Middle Lias of N. Grloucestershhe," by the Eev. F. Smythe, MA. 

 (Proc. Cott. Nat. Club). 



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