﻿92 BRITISH FOSSIL TRIGONI^. 



dental characters in a specimen of the right valve ; the processes are narrow, widely 

 divergent, and have little prominence, corresponding with the internal mould. 



Dimemions. — Height 20 lines, length 27 lines, diameter through the united valves 

 G lines. 



My attention was first directed to this remarkable form by my friend Mr. J. W. Judd, 

 who during his labours in the geological survey of Oxfordshire saw this Trigonia in the 

 collection of Mr. Beesley, of Banbury, and was much struck with its novel aspect. So 

 singular is the combination of characters which it presents, that the term 2^aradoxa might 

 be fitly applied to it were it not already employed in the genus. Its analogues belong 

 altogether to the Cretaceous rocks ; the general outline and also the ornamentation of the 

 anterior side much resembles T. excentrka. Park. The posteal angle and slope with the 

 characters of that portion of its surface assimilate it to some of the cretaceous Scabra, 

 and more especially to T. llondeana, Coq., T. tentdsidcata, Duj., and T. Archiaciana, 

 D'Orb., and this remarkable combination of sectional characters, so foreign to the Jurassic 

 species, occurs in a Trigonia from almost the base of the Lower Oolites associated with 

 a numerous series of Conchifera special to that stage. 



Stratigraphical position and Locality. The two fine examples herewith figured, several 

 others less well preserved, and a few internal moulds, constitute all the materials known ; 

 Mr. Beesley, to whom we owe their discovery, informs nie that the locality of the quarry 

 is Tynehill, in the parish of Adderbury, between that place and Great Barford, Oxfordshire' 

 The rock is coarse, brown, shelly Oolite ; amongst the Inferior Oolite Testacea found with 

 it are Cricopora straminea, Phil., sp., Serpula socialis, Goldf., Natica Lechhamptonensis, Lye. 

 Lima belhda, Mor. and Lye, Nerincea Jonesi, Lye., &c. The specimens figured are 

 from the collection of ]\Ir. Beesley; the University Museum, Oxford, also possesses a 

 specimen. 



Trigonia Michelotti, De Lor. et Pellat {varieti/). Plate XX, fig. 7. 



Lyrodon excentkicum, Goldfuss and Munster. Petrefacta, 183G, vol. ii, page 203, 



plate 137, fig. 8. (Not Trigonia 

 excentrica, Park.) 

 Trigonia Michelotti, T. de Loriol et E. Pellat. Monog. Paleont. et Geol. de I'etage 



Portlaudien des env. de Boulogne- 

 sur-Mer, 18CG, plate 7, fig. 9. 

 — MuNiERi, Hebert. Note sur le terr. jurass. der Boulonuois, Bull, de la Soc. 



Geol. de France, 2 s^r., 1866, torn. 23, page 216. 



' I am unable to determine to which of the eminent French geologists above cited priority should be 

 given, as their publications are dated in the same year. Some consideration is perhaps due to the fact that 

 the beautiful Monograph by De Loriol and Pellat gives the only figure of the species which has appeared 

 since the great work of Goldfuss and Munster, in 1836. 



