Monsieur Delbos, after much research, has determined that the cliffs at Bidart consist of the cretaceous rocks, and that these cease going northward towards Biarritz, and are succeeded by beds of the Lower Eocene. The very lowest of these, however, does not appear on the coast, namely, that which he designates as “Marnes à Terebratules.” The first, which is found to the north, beyond the chalk formation on the coast, is a calcareous rock, containing a species of serpula. Mons. Delbos writes as follows:—

“I now propose definitely the following divisions for the nummulitic deposits of the basin of the Adour.

M. Delbos then gives an explanation of his section of the coast, starting from the point a, and going northward.

“North of the mass of siliceous limestone, of which I have already spoken, and which belongs incontestably to the chalk formation, there is an extensive depression, occupied by sands blown in from the shore, and which interrupts the continuity of the escarpment for the distance of rather more than a quarter of a mile. Beyond this depression the cliff recommences, and from the point where it first appears abundant specimens of fossils characteristic of the nummulitic formation may be collected from a large fragment which lies detached at the foot of the cliff. (Nummulina, Serpula spirulæa, Vulsella falcata, &c.)

In addition to the Brachiopoda noticed in this paper, I am possessed of various minute specimens, which differ from any described species. Some of these may be the young of Brachiopoda that occur in the beds in which they are found; but until their passages into adult shells can be satisfactorily recognized, it will be undesirable to figure or describe them. Three examples of well marked and persistent forms are provisionally named and given below.

Spirifera minima. Moore. Pl. ii., figs. 19, 20.

Shell microscopic, often one sided or unsymmetrical, slightly rugose; valves moderately convex; deltidium triangular; area broad and flattened; hinge-line broad; front of shell rounded, In some specimens the shell presents a uniformly flattened surface, whilst in the majority the outer surface of the smaller valve possesses mesial folds, and in the larger valve a central sinus.

Obs.—This shell is not uncommon in the Inferior Oolite of Dundry. Although no internal characters have yet been noticed, there seems little doubt the shell must be referred to the genus Spirifera. It is perfectly distinct from a little shell found with it, described by me in the Somersetshire Proceedings for 1854. We have thus evidence of the presence of two species of this genus in oolitic strata, although in both instances they have become very degenerate in size. No larger specimens of the genus have yet been found in the same beds to which these diminutive shells can be referred.

Terebratula (?) minuta. Moore. Pl. ii., figs. 21, 22.

I Hope our scientific tourists of the approaching season will take their good eyes into Herefordshire quarries. For now that the Scotch monopoly of the Old Red fishes is broken up, they will be found to repay time and trouble, if searched for in that and the adjoining counties; and something like a reasonable history of these strange old littoral fishes may be the result of a single season's work. There is a great deal about them well worth, knowing, and their remains will be found tolerably abundant, though very fragmentary, both in the sandstones and corn stones; and therefore I have a peculiar pleasure in introducing our primæval fish-fauna to the notice of those on search already—or hoping to be as the season advances—for relics of ancient life.

Before I call particular attention to some fruitful localities, let me say a few words upon the physical condition and geographical aspect of the age they lived in. Though I ought rather to say ages, for they anticipated the advent of the system they are popularly said to belong to—that vast life-era—the extent of whose inland-seas and shallow littoral ocean-zone we see in the sandy, shaly, and gravelly beds which contain our fishes, and of whose deep seas the thick-bedded limestones of Devon are witnesses—called by us Old Red or Devonian; and first appeared upon the stage in true Upper Silurian times; for the Pteraspis Ludensis of the Lower Ludlow shales of Leintwardine (county Salop), is the oldest representative of the family.