Figs. 9 to 12. These fossils are the _Trigonellites_ of Mr. Parkinson; and have since been referred to a genus named _Aptychus_. Their true relations are very problematical. Though found in pairs, there is no hinge or natural connexion. Some naturalists suppose they may belong to the internal organization of Ammonites, because certain kinds have been found collocated with particular species of that genus of Cepholopoda. At present I do not think there is any satisfactory evidence as to their real nature. Species occur in the Kimmeridge clay, and other subdivisions of the Oolite formation. Figs. 9, & 12. _Trigonellites lata_, of Mr. Parkinson. Figs. 10, & 11. ---- _lamellosa_. Figs. 13, & 14. _Corbida revoluta_, of Sowerby. London clay, Highgate. Fig. 16. An imperfect specimen of _Lysianassa_ (_Mya_) _literata_, from the fullers' earth of the Oolite, Wiltshire. Figs. 15, & 17. _Cardita senilis_, of Sowerby. From the Red crag of Suffolk. [Illustration: Plate LXV.] PLATE LXV. Fossil Shells. Fig. 1. A single valve, viewed interiorly, of a fine shell (_Panopæa Aldrovandi_, of Faujas St. Fond) from the Pleistocene or Newer Tertiary strata, that form a chain of low hills near Palermo, in Sicily. The shells in these deposits comprise almost all the genera and species that now inhabit the Mediterranean. They occur in the most beautiful state, deprived only of their colour; and groups are often met with of extreme elegance. The cabinet of the Marquess of Northampton contains an extensive and unrivalled series of these fossils, collected during his Lordship's residence at Palermo. Figs. 2, & 4. A boring bivalve (_Fistulana_ or _Lithodomus_) from the Oolite, Bath. Figs. 3, & 5. Valves of a small Oyster from the Crag of Essex. Fig. 6. A group of Lithodomi in limestone from the Oolite, Bradford, Wilts. Fig. 7. A detached specimen from the same, showing the enclosed bivalve. Figs. 8, & 10. Fine but imperfect specimens of a species of _Teredo_ (_Teredina personata_, of Lamarck), from the Plastic clay of Epernay, France. Fig. 9. A snail-shell (_Helix arbustorum_) found associated, and evidently contemporaneous, with bones of Mammoth, and extinct species of Deer, and other mammalia. From Brentford, in a bed of light calcareous earth, twenty feet below the surface. Fig. 11. "A concamerated Teredo."--_Mr. Parkinson._ I am unable to ascertain the nature of this fossil. Fig. 12. A species of _Fistulana_, from France. Fig. 13. External surface of _Chama squamosa_ of Brander. London clay, Hordwell.