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.

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.

The Inferior Oolite of Yorkshire consists largely of shales and sandstones, which assume much the aspect of a true coal-field, thin seams of coal having actually been worked in them for more than a century. A rich harvest of fossil ferns has been obtained from them, as at Gristhorpe, near Scarborough (Fig. 350). They contain also Cycadeæ, of which family a magnificent specimen has been described by Mr. Williamson under the name Zamia gigas, and a fossil called Equisetum Columnare (see [Fig. 397]), which maintains an upright position in sandstone strata over a wide area. Shells of Estheria and Unio, collected by Mr. Bean from these Yorkshire coal-bearing beds, point to the estuary or fluviatile origin of the deposit.

At Brora, in Sutherlandshire, a coal formation, probably coeval with the above, or at least belonging to some of the lower divisions of the Oolitic period, has been mined extensively for a century or more. It affords the thickest stratum of pure vegetable matter hitherto detected in any secondary rock in England. One seam of coal of good quality has been worked three and a half feet thick, and there are several feet more of pyritous coal resting upon it.