146 SUPPLEMENT TO THE BRITISH 



observable on either side. Beak moderately incurved and truncated by an foramen, 

 slightly separated from the hinge-line by short deltidial plates. Length, 1 inch 4 lines ; 

 width, 1 inch, 1 line ; depth, 8 lines. 



Obs. — This is another of those perplexing ill-defined biplicated forms which can be 

 scarcely distinguished with any degree of certainty. Mr. E. Deslongchamps, to whom I 

 submitted the shells under description, at once identified them with his T. infra- 

 oolitica, and added that they agreed with those he had found in France. The species 

 varies considerably in shape, and seems remarkable from the disposition of its frontal 

 plications, which are situated on a raised mesial fold, somewhat as is seen in Ter. sella 

 from the Neocomian formation. It bears much resemblance to a small variety of Ter. 

 intermedia (var. Laigntonensis) from the Cornbrash of Laignton Herring, near Weymouth. 

 Mr. Deslongchamps states that it forms a connecting link between T. intermedia, 

 T globata, and T. Eudesei, and does not fail to add, " C'est done une de ces especes mal 

 definies, comme nous en avons deja rencontre plusieurs fois, et qui prendront leur 

 caracteres definitifs dans les periodes suivantes." It approaches also much to Ter. 

 Stephani, but in this last-named shell the biplication of the valves is much stronger and 

 more on a level with the almost straight front line. I introduce the species here on 

 the special authority of Professor E. Deslongchamps, who believes that on account of 

 certain small specific differences and its geological position it should, provisionally at 

 least, retain a separate designation. It is also not very unlike some specimens of 

 T. gregaria, Suess, figured by Mr. E. Deslongchamps in pi. viii bis of his ' Brachiopodes 

 Jurassiques.' 



Geological position. — This shell was found by the Rev. F. Smithe in the Ammonites 

 jurensis zone, the base of the Inferior Oolite or passage-beds between the Upper Lias 

 and Inferior Oolite. Mr. E. Deslongchamps and other French geologists place those beds 

 in their " etage infra-oolitique." It is the Falciferen-Zone of Dr. Brauns. Messrs. Tate 

 and Blake in the " Yorkshire Lias " (p. 16) consider the upper portion of Dr. Wright's 

 Upper Lias Sands to belong to the Inferior Oolite, and the lower portion to the Upper Lias. 

 It is, therefore, evident that there is no sharp line of separation between the highest beds 

 of the Upper Lias and the lowest one of the Inferior Oolite. 



I am informed by the Rev. F. Smithe that the Am. jurensis sands are about 150 feet 

 in thickness at Frocester Hill. The specimens of T. infra-oolitica were discovered by him 

 at about the middle of that formation. Terebratula punctata and the var. Haresjieldensis x 

 occurred in the lower Cephalopod-bed lying immediately above the upper portion of the 

 Am. jurensis zone, and Bh. cgnocephala was found in a small ferruginous band over it. 



Mr. E. Deslongchamps states that T. infra-oolitica prevails on the Continent in the 

 lower portion of the Infra-oolite Marls (level of Am. opalinus) in the neighbourhood of 

 Potiers, of Niort, Saint-Maixent, Montreuil-Bellay, &c. (Dep. des Deux Sevres), and 

 in several others. 



1 In the first part of this Supplement the name Haresfield has been inadvertently spelt with a v. 



