4. A specimen, being a mass of comminuted fragments of shells, amongst which are only recognizable a few segments of the column of the encrinus, and minute turretted univalves of five whirls, which resemble turritella, and are about one-twentieth of an inch long.
5. _Millepora cylindrica_, SAY.--Branched, cylindric; _pores_ very regular, alternate, oval, placed nearer to each other than the length of their own transverse diameters, and resembling those of an _alveolite_.
6. Segments of the column of encrinus of authors, of a pentangular form.
7. Ossiculæ of the body of a crinoid animal of the analogous species to No. 21.
9. A mass of argillaceous sandstone, containing spines of a Linnæan echinus, belonging probably to the genus cidarites of Lamarck. Of these spines some are elongate-conic, others slightly fusiform, obtuse and slightly dilated near the tip, both are armed with short asperities throughout their length. They resemble in some degree those of the _cidarites pistillaris_ of Lamarck, but they are smaller, less fusiform, and the asperities are not prominent.
In the same mass are segments of encrinus, and fragments of the retepore.
10. Retepore, much resembling the _milleporites flustriformis_ of Martin, Petrif. Derbi. pl. 43. fig. 1 and 2., but the alveoles in our specimens are rather smaller.
11. _Millepora cylindrica_, SAY.--Of the diameter of half an inch.
12. _Productus subserratus_, SAY.--Shell transverse, convex valve semicircular, destitute of asperities or striæ, longitudinally indented in the middle; line of the hinge rectilinear, half as long again as the length of the shell, with three or four spines or serratures on each side towards the angle; _umbo_ not prominent; the beak hardly prominent beyond the line of the hinge. Length, more than three-tenths; breadth, more than half an inch. A large specimen was four-fifths of an inch wide.
If we except the beak, the outline of this shell, as respects the hinge margin and the sides, considerably resembles that of P. _spinulosus_ of Sowerby, but the base is far more obtusely rounded, and it is a shorter shell comparatively with its width. The serratures are very often broken off. The curvature of the sides does not in the slightest degree project beyond the angles of the hinge line.