Where now is that great funereal mass ? Where now that twothousand feet of ocean mud and sand ? All round the rim of the great Wealden area the basset-edges of that thick mass crop out, bearing on their cliff-like downs patches of red loam, gravel and round flint-pebbles—remnants that mark the ravages of time and physical forces upon the rock-beds of yet another age, in which that great Cretaceous mass was slowly raised, bearing as it were on its shoulders the ever-forming ooze, filled with the relics of other intervening forma of life that reigned in that vast interval between the Secondary period and our own.

In making the excavations now in progress for the formation of the great South High Level Sewer in the neighbourhood of Peck-ham and Dulwich, the works have been carried through a series of deposits, constituting part of the lower London, Tertiaries, and distinguished by Mr. Prestwich as the “Woolwich and Reading series.” As I learn from Mr. Charles Rickman, the able and zealous curator of the Lambeth Museum of Natural. History who has laboured assiduously in collecting the fossil remains found in them, these deposit at Dulwich, at the depth of twenty-five feet from the surface, comprise a bed of grey sand, and below this, at a depth of about forty feet, and intercalating a bed of clay containing, shells and a bed of Ostreæ, a band of hard compact sandstone, very slightly calcareous, apparently identical with that at Lee, referred to by Mr. De la Condsmine as known there by the name of the “cookle.”

In a former communication to the “Geologist,” treating of the fossil fauna and flova observed in Lower Eocesie sttata passed through at Dulwich and Peckhem in the constraction of the Great South High Level Sewesu I mentioned the fact of having discovered in a shelly conglomerate, at Dulwich, a new species of the estuarine genus Gyrena which I proposed to call Cyrena, Dulurichieæsis. In sinking the main shaft, at a depth of fifty to sixty, feet this eonglomerate occurred in nodular masses in green shelly sand, intercalated with wedge-like bands of stiff black clay, highly charged with vegetable remains; bat on driving the gallery eastward the conglomerate became regularly bedded, and attained a maximum thickness of four feet, made up plentifully of the shells of Cyrena cumeiformis, C. cordata, C. Dulwichiensis, Melania inquinata, and the new genus Pitharella, now figured and described by Mr. Edwards. I annex a description of the distinguishing generic characteristics of the Cyrena Dulwichiensis, and, as an accompaniment to the figure, some of the prominent peculiarities noticeable in the species.

The greater part of the main road from Carillon to Grenville, a distance of thirteen miles on the northern banks of the Ottawa River, runs over the Calciferous sand rook of the Lower Silurian formation. In many places ihe surface of the rock is exposed, and beyond the village of Chatham, towards Grenville, and even in Chatham, for a short distance, the road consists of the solid limestone rock. As the surface of the rock is more or less rough or uneven, the road is an uncomfortable one to travel over in a wheeled vehicle. On driving over that part of the rock just near Chatham, a tremendous loud rumbling noise is occasioned by the stage, which is not heard, in other situation. This has been attributed to the presence of one or more large caverns situated beneath the road at this place: and, on making inquiry on the spot, I learnt that a prevalent opinion has long been entertained by the country people and many intelligent persons in the to neigbourhood, that a considerable cavern does exist in this part of the country in the place mentioned. On the many occasions that I have driven over this road, the loud rumbling noise has been invariably observed by my fellow travellers as well as by myself. Sotne-day an opening into the cavern may be discovered and the mystery solved. The main road is, elevated and is probably from seventy to ninety feet above the level of the Ottawa River.

The shells composing this species vary but slightly in shape, being marginally semicircular, concavo-convex, and about one-third wider than long. The hingeline is straight, and either a little shorter, with its cardinal angles rounded, or somewhat longer than the greatest width of the shell, with rectangular or slightly acute and extended terminations. Both valves are provided with narrow sub-parallel areas, the ventral one, which is the largest, being divided by a small fissure, partially covered with a pseudo-deltidium; while in the middle of the ventral one there exists a prominent V-shaped cardinal process. The ventral valve is moderately convex, and flattened towards its auriculate cardinal extremities. The beak, which is small and incurved, does not overlie the hinge-line; while the dorsal valve assumes in different specimens a greater or lesser degree of concavity, and follows the curves of the opposite one. Exteriorly the surface of the ventral valve is covered with numerous small thread-like radiating striæ, which increase in number by occasional bifurcation, or interstriations at various distances from the beak, so that as many as one hundred and twenty ribs may be counted round the margin of certain specimens, while at irregular distances small spines projected from the rounded surface of the striæ. In addition to these, on each side of the beak there exists along the cardinal edge from five to nine slanting tabular spines, which become longer and larger as they approach the extremities of the cardinal edge. The surface of the dorsal valve is striated as in the ventral one; and minute perforations or punctures may be perceived over the entire surface of the shell, and which are the exterior orifices of the canals which traverse the shell, as in Productus.