84 BRITISH FOSSIL TRIGONI^. 



Sfratip'npJncal position and Localities. The Brora specimens are in a pale whitish 

 argillaceous grit, which Mr. Judd believes to be upon the horizon of the Lower Calcareous 

 Grit of Yorkshire ; they are associated with Pecten vimineus, Sow, 



§ IV. Glabrae. 



Trigonia gibbosa, Sow. Plate XVIII, figs. 1, 2, 2 a, 3, 4, 5, 6 ; Plate XIX,^ 



figs. 1, 1 «, 1 b, 2. 



Trtgonia Gibbosa, Soiverby. Min. Conch., tabs. 235, 236, p. 61, vol. iii. 



— _ Benett. Catal. Org. Eem. County of Wilts, 1831. 



— — Deshayes. Coq. Carac, 1831, pi. xi, fig. 8, p. 57, 1831. 



— — Be la Beche. Manual of Geology, 1833. 



— _ Fitton. Geol. Trans., 2 ser., 4, p. 356, 1835. 



— — Pusch. Potens Paleont., 1837, p. 60. 



— — Fitton. Bull. Soc. Geol. de France, 1839, I ser., torn, x, p. 445. 



— — Agassiz. Trigonies, 1840, p. 10. 



— — Bronn. Index- Pale'ont., 1848, p. 686. 



— — B'Orbigny. Prodrome de Paleont., 1850, vol. ii. No. 42, p. 60. 



— — Buviffier. Statist. Miner, et Geol. Meuse, pp. 370, 401, 1852. 



— — Morris. Catalogue, 1854, p. 228. 



— — Pictet. Traite de Paleont., t. iii, p. 539, 1855. 



— — Hebert. Terr. Jurass de la Bassin de Paris, p. 73, 1857. 



— — Oppel. JuraformatioD, p. 722, No. 144, 1856. 



— — Contejean. Etage Kimmeridgien deMont Belliard, pp. 60 et 217, 



1859. 



— — Coquand. Synopsis des Foss. de la Charent., 1860, p. 36. 



— — Rigeaux. Notice Stat, sur le Bas Boulonnais, 1865, p. 26. 



— — Pellat. Bull. Soc. Geol. de Fr., 2 ser., torn, xxiii, pp. 208, 209,. 



1866. 

 ■ — — H6bert. Note sur le terrain Jurassique du Boulonnais, Bull. Soc. 



Geol. Fr., 1866, 2 ser., torn, xxiii, p. 21. 



— — Be Loriol and Pellat. Monog. Paleont. et Geol. de I'e'tage 



Portlandien des env. de Boulogne, 

 1866, pi. iii, figs. I, 2, 3. 



— — Wright. Correlation of Jurassic Rocks, Proceedings of Cottes- 



wold Nat. Club, 1869, p. 88. 



Shell somewhat inflated, sub-ovate, or ovately oblong; umbones large, obtuse, 

 elevated, antero-mesial and erect ; anterior and inferior borders elliptically curved, hinge- 

 border concave, its posteal extremity curved gently with the posteal border of the area. 



