Near the same place a reddish sandstone occurs in which are innumerable traces of a fossil vegetable, apparently _ Sphenopteris,_ the stems and branches of which are disposed as if the plants were standing erect on the spot where they originally grew, the sand having been gently deposited upon and around them; and similar appearances have been remarked in other places in this formation.[3] In the same division also of the Wealden, at Cuckfield, is a bed of gravel or conglomerate, consisting of water-worn pebbles of quartz and jasper, with rolled bones of reptiles. These must have been drifted by a current, probably in water of no great depth. Fig. 296: Sphenopteris gracilis. From such facts we may infer that, notwithstanding the great thickness of this division of the Wealden, the whole of it was a deposit in water of a moderate depth, and often extremely shallow. This idea may seem startling at first, yet such would be the natural consequence of a gradual and continuous sinking of the ground in an estuary or bay, into which a great river discharged its turbid waters. By each foot of subsidence, the fundamental rock would be depressed one foot farther from the surface; but the bay would not be deepened, if newly-deposited mud and sand should raise the bottom one foot. On the contrary, such new strata of sand and mud might be frequently laid dry at low water, or overgrown for a season by a vegetation proper to marshes. Punfield Beds, Brackish and Marine.—The shells of the Wealden beds belong to the genera _Melanopsis, Melania, Paludina, Cyrena, Cyclas, Unio_ (see Fig. 294), and others, which inhabit rivers or lakes; but one band has been found at Punfield, in Dorsetshire, indicating a brackish state of the water, where the genera _Corbula, Mytilus,_ and _Ostrea_ occur; and in some places this bed becomes purely marine, containing some well-known Neocomian fossils, among which _Ammonites Deshayesii_ (Fig. 284) may be mentioned. Others are peculiar as British, but very characteristic of the Upper and Middle Neocomian of Spain, and among these the _ Vicarya Lujani_ (Fig. 297), a shell allied to Nerinea, is conspicuous. By reference to table (p. 308) it will be seen that the Wealden beds are given as the fresh-water equivalents of the Marine Neocomian. The highest part of them in England may, for reasons just given, be regarded as Upper Neocomian, while some of the inferior portions may correspond in age to the Middle and Lower divisions of that group. In favour of this latter view, M. Marcou mentions that a fish called _Asteracanthus granulosus,_ occurring in the Tilgate beds, is characteristic of the lowest beds of the Neocomian of the Jura, and it is well known that _Corbula alata,_ common in the Ashburnham beds, is found also at the base of the Neocomian of the Continent. Fig. 297: Vicarya Lujani. Fig. 297: _Vicarya Lujani_, De Verneuil.[4] Wealden, Punfield.