In 1854 the remains of another mammifer, small in size, but larger than any of those previously known, was brought to light. The generic name of _Stereognathus_ was given to it, and, as is usually the case in these old rocks (see p. 328), it consisted of part of a lower jaw, in which were implanted three double-fanged teeth, differing in structure from those of all other known recent or extinct mammals. Plants of the Oolite.—The Araucarian pines, which are now abundant in Australia and its islands, together with marsupial quadrupeds, are found in like manner to have accompanied the marsupials in Europe during the Oolitic period (see Fig. 348). In the same rock endogens of the most perfect structure are met with, as, for example, fruits allied to the Pandanus, such as the _Kaidacarpum ooliticum_ of Carruthers in the Great Oolite, and the _Podocarya_ of Buckland (see Fig. 347) in the Inferior Oolite. Fuller’s Earth.—Between the Great and Inferior Oolite near Bath, an argillaceous deposit, called “the fuller’s earth,” occurs; but it is wanting in the north of England. It abounds in the small oyster represented in Fig. 349. The number of mollusca known in this deposit is about seventy; namely, fifty Lamellibranchiate Bivalves, ten Brachiopods, three Gasteropods, and seven or eight Cephalopods. Fig. 347: Portion of a fossil fruit of Podocarya Bucklandii. Fig. 348: Cone of fossil Araucaria sphærocarpa. Fig. 349: Ostrea acuminata. Inferior Oolite.—This formation consists of a calcareous freestone, usually of small thickness, but attaining in some places, as in the typical area of Cheltenham and the Western Cotswolds, a thickness of 250 feet. It sometimes rests upon yellow sands, formerly classed as the sands of the Inferior Oolite, but now regarded as a member of the Upper Lias. These sands repose upon the Upper Lias clays in the south and west of England. The Collyweston slate, formerly classed with the Great Oolite, and supposed to represent in Northamptonshire the Stonesfield slate, is now found to belong to the Inferior Oolite, both by community of species and position in the series. The Collyweston beds, on the whole, assume a much more marine character than the Stonesfield slate. Nevertheless, one of the fossil plants _Aroides Stutterdi,_ Carruthers, remarkable, like the Pandanaceous species before mentioned (Fig. 347) as a representative of the monocotyledonous class, is common to the Stonesfield beds in Oxfordshire.