APPENDIX.

APP. A.

Descriptive Notes respecting the Shells figured in Plates XI. to XXIII. By JAMES DE CARLE SOWERBY, F.L.S. &c.

PLATE XI.

Fig. 1. Tornatella elongata. Elliptical, elongated; surface furrowed; furrows crossed by short lines; whorls about four; lip slightly thickened. This resembles Acteon (Tornatella) simulatus (Min. Con. t. 163. f. 2.) of the London clay, even in the dotted furrows upon the surface of the shell, but it is much longer in proportion, and is only half the size.

Fig. 2. Lucina? globosa. A nearly globose smooth shell, with the lines of growth peculiarly waved near the posterior margin. I have not seen the interior.

Fig. 3. Avicula Gryphæoides. The convex valve nearly orbicular, with a projecting incurved beak, and two small unequal ears: when alone, it may easily be mistaken for Inoceramus concentricus, but the parts about the beak, especially the ears, show the difference. The other valve is nearly flat, orbicular, and has one small and one large ear. The convex valve a. is represented from specimens found at Nursted in Hampshire; the other valve, b. is from Cambridgeshire.

Fig. 4. Pentacrinus. The stem only has yet been found; it is various in size, the sides are concave, the angles rounded. Joints equal, the margins of their surfaces ornamented with short striæ. Some specimens show the bases of lateral arms. It strongly resembles a species found in the chalk ;-(Mantell; Fossils of the South Downs, p. 183; Geol. of the S. E. of England, p. 112.); which is, however, much larger.

Fig. 5. Pollicipes lævis. The lateral valves are rhomboidal, smooth, thin, and nearly flat: in the partially decomposed state in which they are found, they appear to be composed of layers, of different degrees of transparency and depths of colour. This species also occurs in the greensand at Blackdown: see Plate XVI. fig. 1.

Fig. 5. Pollicipes unguis.

portion to their length.

Smooth, the valves are all remarkably curved, and broad in pro

Fig. 6. Pollicipes radiatus. Valves wedge-shaped, flat, marked with sharp, elevated rays, diverging from their apices.

Fig. 6. Pollicipes rigidus is distinguished by thin transverse elevations, which are very prominent upon the posterior valves: the lateral valves are elongated.

Fig. 7. Venus? tenera. Shell lenticular, rather transverse, neatly marked with concentric striæ; lunette lanceolate.

Fig. 7. Venericardia tenuicosta. Transversely oblong, approaching to square. It varies much in convexity: and when old or interrupted in its growth, is nearly globose, rather heartshaped. Specimens have been found twice the length of that represented in the figure, both of the oblong and globose form. The surface of the rays is rough, with slightly elevated obtuse scales. The interior of the margin is crenated. Lunette rather deep, heart-shaped.

Fig. 8. Nucula bivirgata. Very convex; the surface ornamented with two sets of linear furrows, which meet towards the posterior slope, at acute angles directed towards the beak of each valve; the junction producing a regular line, without forming a ridge. Lunette broad.

Fig. 9. Modiola bella. Neatly striated, convex, with parallel edges, nearly equal sides, and

obtuse beaks.

Fig. 10. Lima semisulcata. (Plagiostoma semisulcatum, Nilsson, Petrif. Suec. 25, t. ix. f. 3.) Ovate elongated, very convex, the beaks incurved, short; ears nearly equal, sinall. Where the lines of growth cross the ridges, which vary in number from 11 to 16, they form obtuse, short scales or grains.

Fig. 11. Auricula inflata. (Benett's Catalogue of Wiltshire Fossils, 4to, p. 2.) Shell ovate; spire small, pointed; the last whorl large; aperture at the lower part approaching to square, but with one of the upper angles elongated and acute; the lips united, thick, obtuse; the columella has two plaits, the lower sometimes divided by a groove along its middle. The surface of the shell is marked with numerous spiral lines of elongated punctures. The thick lip separates this from several species of Tornatella, to which in other respects it bears a strong resemblance. Auricula incrassata of Min. Conch. t. 163. is shorter and smaller, and has the lip more enlarged. A. incrassata of Mantell (Geol. Sussex, t. xix. figs. 2, 3, and 34.) also resembles it, but has a much shorter spire.

Fig. 12. Natica canaliculata. (Ampullaria canaliculata, Mantell, Geol. Suss. tab. xix. fig. 13.) Globose, depressed, smooth. Umbilicus large, circular, gradually expanded into the base. Around the upper edges of the whorls is a concave, transversely striated groove, best defined in the young shell,-as in c. The inferior specimen, a. b. is filled with brownish phosphate of lime. See the figure of a much larger specimen, Plate XVIII. fig. 6.

Fig. 13.

Solarium ornatum. Discoid, with a small portion of the spire elevated and acute; aperture rhomboidal. Surface, above ornamented with obtuse, radiating ribs,-and near the margin, both above and below, with granules in quincunx order.

Fig. 14. Solarium conoideum. (Min. Conch. t. 11.) A conical shell as high as it is wide; the umbilicus large and smooth. The outer coat of the shell is represented in this figure; and shows the upper part of each whorl to be concave, and elegantly marked with decussating striæ forming rows of granules; aperture rhomboidal, nearly square.

Fig. 15. Pyrula Smithii. Ovato-fusiform; two obscure keels and numerous striæ wind round its surface; spire rather elongated, acute. These two figures, perhaps, represent different species fig. a. is more distinctly keeled than fig. b., which, however, being considerably worn, has lost much of its external sculpture; but shows also longitudinal undulations, which can hardly be traced upon fig. a. Both the specimens are from Copt Point, near Folkstone. Murex Smithii (Min. Con. 578), lately removed to the genus Pyrula, is a different shell.

Fig. 16. Rostellaria elongata. Presumed to be a Rostellaria, from its resemblance to R. marginata, fig. 18.; from which it differs principally in its great length and the smaller number of ribs. Turrited, much elongated, ribbed, transversely striated; upper edge of the whorls smooth. Fig. 17. Rostellaria buccinoides. A neat, subulate, costated shell, approaching to R. rimosa : it has but one varix upon each whorl : the lip is not lobed.

Fig. 18. Rostellaria marginata. Turrited, conical, transversely striated; ribs eight or ten upon each whorl, short and obtuse; last whorl keeled, without ribs. Named from a ridge or narrow band upon the upper edge of each whorl; which is more or less conspicuous in every specimen, and assists in distinguishing the species from Rostellaria Parkinsoni. See Pl. XVIII. fig. 24.

Fig. 19. Rostellaria carinata. (Mantell; Fossils of the South Downs, p. 86, Pl. XIX. figs. 10, 11, 12, and 14.) This figure, from a drawing by the Rev. G. E. Smith, exhibits the lip in an advanced stage of growth. The spire is nearly subulate, composed of eight or nine convex whorls; a row of small tubercles, or short ribs, winds round the middle of each whorl except the last,

which has two acute keels; the lip has a long forked projection arising from the upper keel; the beak is long and subulate; the whole surface striated.

Fig. 20. Ammonites? circularis. Aperture circular; whorls just touching each other: nearly close, acute, circular; sometimes forked ridges cover the surface. This specimen may, perhaps, be a portion of an Hamites or Scaphites?

Fig. 21. Ammonites symmetricus. Aperture nearly square; ribs blunt, slightly tumid as they approach the hollow in which the rounded keel is immersed, and though not equal in length, elegantly uniform in their elevation; the sides of the whorls flattened. The specimen here figured, though a fragment only, differs from every Ammonite known to me.

Fig. 22.

Ammonites crenatus. Sides flattened; the inner whorls much exposed, their margins nearly smooth and rounded, those of the outer whorls crenated on each side of a narrow concave space over the siphuncle. Distinguished from A. splendens by the more exposed inner whorls.

Fig. 23. Ammonites cristatus. (De Luc, in Brongniart, Env. de Paris, pl. vii. 10.) Some of the ribs being acute and much more elevated than others, form the distinguishing character of this species. I believe A. cristatus and A. subcristatus of De Luc to be varieties of the same species: I have seen both from Folkstone: the specimen before us belongs rather to the latter variety.

PLATE XII.

Figs. 1, 2. Hamites rotundus. (Min. Conch. tab. lxi. fig. 2, 3.) The peculiar structure of the inner extremity in this species, is indicated, rather than distinctly seen, in these figures; which have been engraved from drawings by the Rev. G. E. Smith, taken from specimens collected by Lord Greenock, near Copt Point in Kent. Mr. Smith observes, in a note sent with the drawings, that the termination in a minute whorl, (imperfectly seen in the figures,) had been traced distinctly in more than one specimen; which proved that the coils of the spiral were nearly parallel to the straight part of the stem, and the axis at right angles to it. The spiral appears to have been open, as in many recent Serpulæ; so that its perfect preservation in the fossil could scarcely have been expected and this would account for the defective state in which the Hamite is commonly found. Mr. Smith adds that the spiral portion appeared invariably to have been decayed, as if it had been filled up with soft matter, as in the case of Magilus. The figures show the remains of the spiral, in two different specimens; but in both much broken and displaced. The spiral part is round, with contiguous annular ribs, also round and regular.

Fig. 3. Hamites attenuatus. (Min. Conch. t. Ixi. fig. 4. and 5.) Both ends of this species, when complete, are similarly bent or folded in, not spirally, but so that the segments become parallel to each other. The larger parts are rather compressed, the smaller cylindrical; the ribs are annular and rounded.

Fig. 4. Hamites spiniger. The general form of this species is like that of Scaphites Yvanii, (Bull. de la Soc. Géol. de France, vol. ii. p. 355, pl. ii.); one portion being a flat volute, like an Ammonite, but with unconnected whorls; the other bent into the characteristic form of a Hamites: the sides are flattened. The spines form one of the chief specific characters: there are three rows of them on each side, placed upon the larger ribs on the involute part of the shell; they are gradually lost upon the other parts.

Fig. 1.

PLATE XIII.

Echinus? arenosus. The underside is imperfect, and the genus therefore doubtful. Fig. 2. Panopaa rotundata. Only a cast, which is nearly smooth. The ridge separating the posterior area, which is small, is strongly marked, and projects on the margin.

generally, in England, as no more than in a particular and subordinate bed of the Glauco-ferruginous sands*.

7. Grès glauconnieux; Grès vert.—(PORTLAND-STONE and Sand.)

These terms are applied to green-sand passing into grit, which again passes into a calcaire glauconnieux. Both the grit and limestone are full of green particles: they alternate with beds of sand, and are generally quarried throughout the Pays de Bray: and the grès calcaire is stated to be identical with that observed by M. Rozet, at Mont Lambert in the Boulonnois. Among the fossils are Ammonites; Crassatella; Cucullæa; Ostrea; Serpula; Trigonia; and teeth of the Diodon. M. Passy justly expresses doubt whether this grit has hitherto been recognised in England. I believe it to belong to what I have proposed to call the Portland-sand; the characters and relations of which, though long since generally intimated by Mr. Conybeare, have not hitherto been fully understood in England: and, from my own observation, I have no doubt that some of the concretional masses of the Boulonnois belong to this part of our series. It will be observed, on comparing M. Passy's sections with those in the interior of England, that the lower greenish grit (Portland-sand) of M. Passy †, is not conformable to the beds above;—a fact analogous to the existence of chasms and "gullies", in the Lower Purbeck, and upper part of the Portland strata, in Oxfordshire and Bucks:-supra (111.), p. 218; (141.), p. 265; (144.), p. 276, (151.).

8. Calcaire glauconnieux ;-a limestone composed of fragments of shells, united by sparry carbonate of lime, containing green particles, rolled grains of quartz, and flints of different hues. The fossils include Ostrea gregarea, and other indistinct species; Trigonia; and Crassatella. The limestone in this group alternates with grit, and includes a bed of green or bluish marl. The whole belongs to the group between the Portland-sand and the Oxford-oolite in the Lower Boulonnois and is represented in England by part of the series on the coast near Weymouth. 9. Marne et calcaire marneux;—à Gryphæa Virgula; Calcaire lumachelle.

The strata of this group are described as occurring unconformably-(" étendues en couches discordantes"), beneath the ferruginous sands: a statement which accords with the relations of the group to the Upper green-sand,-but not to the sands of Portland. The formation is characterized by Gryphæa Virgula, and some of the beds contain Ostrea deltoidea. On the coast, from Havre towards Henqueville, it occupies a thickness of 30 metres (about 100 English feet), between the chalk and the oolite; and it seems to be the equivalent of the series of shale, limestone, and calciferous grit abounding in petrifactions, which connects the Kimmeridge-clay with the Oxford oolite, on the coast of the Boulonnois, and of Dorsetshire.

10. The lowest strata of the Pays de Bray "consist of blackish compact limestone, like that of "Marquise in the Lower Boulonnois;-the carboniferous limestone of England:" and these succeed immediately to the group last mentioned. If this be so, the oolitic series, from the Oxford oolite to the bottom of the lias, is wanting; together with new red sandstone and the coal formation-another point of resemblance to the Lower Boulonnois.

(168.) Marine deposits coeval with the Wealden.—It is obvious that, during a period of time sufficient for the accumulation of the Wealden, the deposition of matter in the adjacent seas could not have been inconsiderable; so that we might expect to find, interposed between the strata which then formed the

....que l'argile Veldienne qui contient les coquilles d'eau douce, n'est qu'une couche "particulière de terrains glauco-ferrugineux d'Angleterre."-p. 256. Passy, p. 272; and Plates I. and II. Ibid., p. 262, 265.

bottom of the sea, and the Lower green-sand, a series of beds coeval with the Wealden in point of date, but differing from it in possessing the characters of a marine deposit, and including marine shells and other productions of salt water;—with which, near the shore, the productions of the land, or even the freshwater shells of the rivers, might be occasionaly intermixed. And if the Portland strata constituted at that epoch, both the dry land, and the bottom of the sea, and were afterwards submerged, we ought now to find the Lower greensand, in some places immediately in contact with the Portland,― in others with the Wealden,—and in others again with the marine equivalent of this latter group.

Two results would probably attend the state of things here supposed, which are deserving of notice: 1st, That the Wealden and its marine equivalent could not both be found in the same place; and consequently, (since we have the former in England), that the marine beds of that date are not to be expected generally in this country: 2ndly, That the marine fossils of the beds cotemporaneous with the Wealden would probably be distinct, both from those of the Portland group beneath, and of the Green-sands above them; a consideration which gives peculiar interest to the fossils of this intermediate group.

The strata between the chalk and the oolitic system on the continent of Europe have not yet been sufficiently examined, to furnish all the evidence that may be expected upon this subject; but indications of such an equivalent to our Wealden as has been mentioned, have been already found in so many detached points, that its occurrence in other places, or even the existence of a continuous marine deposit of that age, is by no means improbable. Mr. De la Beche✶ has brought together evidence which shows that such a group exists in the department of the Haute Saône, in France; at Candern, in the Brisgau; near Aarau ; in Poland; and on the confines of Silesia. To these may be added the Isle of Bornholm in the Baltic, and the vicinity of Helsingburg, in Scania, which have afforded specimens of fossil plants resembling those of our Wealden, along with marine shells; but at Bornholm, although the shells are also marine, they are generally such as may be supposed to have inhabited, either the estuary of a large river, or the seas immediately adjacent to the coast.

In most of the cases mentioned by Mr. De la Beche, a group of strata between the chalk and the oolitic system is found to contain pisiform iron ore; but the fossils which accompany that mineral are marine. A very extensive deposit of this kind in Poland and Silesia is described by Professor Pusch, which includes also argillaceous iron ore; and among its fossils are the genera Ammonites, Geological Manual, (1833.), p. 309.