In our second group are provisionally assembled a number of Tere-bratula-shaped species, with a curved hinge-line, no defined area, beak entire, or truncated by a circular foramen for the permanent or temporary passage of a peduncle, and with spiral appendages directed outwards, as in Spirifera, but connected by a more complicated system of lamellæ. Much has, however, to be discovered concerning the interior details of the larger number of the species before we can hope to establish permanent and satisfactory divisions in this group.

The genus Athyris has for years attracted the notice of palæontologists, but it. was not until a recent period that all its important characters could be established. The species vary considerably in their external shape; they are circular or angular, elongated or transverse, smooth, ribbed, or striated, some have the entire surface of their valves covered with numerous concentric plates, which are prolonged in many instances nearly an inch from the surface of the shell, while in other species the valves are covered by a vast number of scaly ridges from which radiate closely-set fringes of elongated, somewhat flattened spines; and so close are these sometimes in their arrangement, that no portion of the shell can be distinguished.

II. It is about a mile across the Lower Lias, on which the villages of North Cave and Hotham are situated, to another gently-rising ground which ascends out of Hotham Park to the eastward in a beautiful sloping bank, and being tastefully planted with stately trees, contributes very much to the charm of the scenery. Coming in with my hammer to the ancient village, in the bright and odorous evenings of midsummer, I have often been arrested by the sweetness of this place; and, enamoured of its serene and peaceful beauty, I have loitered to admire its dark plantations, and the greensward slope that I am now describing, and the illuminated wold rising high in the distance. It is the low escarpment of the Middle Lias which declines thus pleasantly into the park at Hotham. A.s we go out of North Cave towards Beverley, this bank may be observed to rest upon soft blue shales, which have hitherto supplied no fossils. When we begin to ascend it, we may turn into a copse on the right-hand side and study the section in a marl-pit, or we may notice the roadside cutting. In either case, we shall observe that the beds change as follows:—From blue shales at the bottom and lower part of the ascent, through brown earthy-looking shales and sand with irregular broken bands of nodular clay-ironstone, one of which enclosed a cast of Unicardium cardioides, to a hard rock-bed of the true Marlstone, two or three feet in thickness, which again is capped at the top of the ascent by a very rusty, rubbishy, and ferruginous rock.