Oxford,' p. 325); and the beds of this mineral met with in the subWealden boring may possibly belong to the uppermost portion of the formation. This is one gypsiferous zone; there is another below, seen at Hawkstead. Following on this, at the Wrawby-road bridge, are the clays with Amm. serratus and associated fossils. We here reach the region most interesting by its organic remains, which are in great variety and tolerable abundance. Pits in this zone are numerous, though not all containing the same fossils. At Wrawby occur the following : Ammonites biplex, Sow. serratus, Sow. Thracia depressa, Sow. Anatina minuta, Bla. Astarte supracorallina, D' Orb. At Market Rasen, on the north side of the Louth road, is the pit in this region which appears to be opened on its most fossiliferous part; and from this and another on the Walesby road, nearly on the same horizon, but a little lower, have come most of the Lincolnshire Kimmeridge-clay fossils of late years. It is covered by a few feet of sand redeposited from superjacent beds; and then we have 17 feet of blue clay most fossiliferous towards the base, 6 inches of septarian limestone, and blue clay 2 feet. The best fossils lie nearest to the limestone, above and below, but not in any wellmarked horizons. The commonest, besides the Ammonites cymodoce, decipiens, and serratus, are the characteristic Astarte, a new species of Cerithium, Nucula Menkii, and Thracia depressa. Ostrea deltoidea, though present, is very rare, as is also Lingula ovalis. The complete list, richer than from any other locality and containing several new forms, is as follows: Ichthyosaurus, sp. Ammonites decipiens, Sow. mutabilis, Sow. ? rotundus, Sow. Belemnites nitidus, Dollf forticostatum, Bla. Lucina minuscula, Bla. Astarte supracorallina, D'Orb. At Holton-Moor Station, as before mentioned, a brickyard in this region occurs with similar fossils, as far as examined—that is, those that are most common at Market Rasen, with the addition of Pholadomya ventricosa (Sow.). More to the south two important pits in this region are seen on the Wragby and Horncastle road, called the Baumber and Langton pits. The latter, from its stratigraphical position, must be lower in the series than the former; yet its characteristic univalve is Rostellaria mosensis, showing how little reliance can be placed on that shell as indicating a zone. Neither of these is so rich as that at Market Rasen; and they have, besides, been less worked. At Baumber two rows of doggers are visible-one smaller set near the top, and another of immense ones at the base. Many of these contain Amm. Berryeri like those of the region above, but Amm. serratus is also plentiful. Blue clay, 20 feet thick, lies above these latter doggers, and in places it is really difficult to say whether the fossils or the clay compose the greater part of the bed; but the fossils are difficult to preserve and much broken. The fossils obtained here are: Ammonites Berryeri, Les. hector, D'Orb. Astarte Michaudiana, D' Orb. Homomya compressa, Ag. arcuatus, Sow. Lima ædilignensis, Bla. Lingula ovalis, Sow. At Langton less of the clay is seen before reaching the doggers; but this would seem to arise from the fact that there are many rows of doggers in the clay, and the brick-pits are excavated till the first is reached, since they always lie at the base. The doggers here are brown when exposed to the air, being more or less ferrugiThe assemblage of fossils is remarkable-Rostellaria mosensis, as mentioned before, being abundant, with Nucula obliquata, which also belongs to a higher part, yet associated with several fossils (Serpula tetragona, Cyprina cyreniformis, and Avicula ædilignensis) which become common in the beds below. The species are :— nous. Ammonites Berryeri, Les. serratus, Sow. Rostellaria mosensis, Buv. Arca rhomboidalis, Cont. Avicula ædilignensis, Bla. A small pit on the Caistor Road, near Market Rasen, which, from its stratigraphical position, is lower than those before mentioned, seems, from its fossils, to be most comparable with that of Baumber, i. e. by the large Amm. Berryeri and abundant Lingula ovalis; but its more numerous Market-Rasen fossils associate it more closely with the pits there. Here are found: - The number of pits on this horizon and their wide separation seem to indicate considerable total thickness. They may be considered to form a second subzone. Exposures of beds below this level exhibit, as remarked by Mr. Judd, a well-marked difference, both lithologically and palæontologically, but still not sufficient to warrant a separation, though the difference is far more marked than anywhere else below the Upper Kimmeridge, in Lincolnshire-so much so that the first time I saw these lower beds after seeing those of Market Rasen I took them to be Oxford Clay. This was at a well-sinking on the Bishopsbridge Road, about 11⁄2 mile east of the pit last mentioned. Here were black clays with white rotten fossils in layers, most of them being undistinguishable (apparently Pholadomyæ); but Ostrea dilatata and Belemnites were plentiful; and there were some reptilian remains, consisting of very compressed vertebræ and long bones. On one of these, however, were numerous Discina, which, though badly preserved, showed the fine radiating striae of Discina Humphresiana. The Belemnites too were not hastate, but comparable with B. nitidus. However, the age was settled on discovering in a cutting, west of the Wrawby cutting before mentioned, exactly similar black clays in the same stratigraphical position, containing also Ostrea dilatata and deltoidea and abundance of Belemnites nitidus, associated with : Ammonites, sp. (? young of deci- Rissoa mosensis, Buv. Anatina minuta, Bla. Serpula tetragona, Sow. : Trigonia, sp. (cast, elongated). Corbula Deshayesia, Buv. Anomia Dollfusii, Bla. Lima ædilignensis, Bla. Some of these which do not occur higher up are seen again, with Ostrea deltoidea, at Woodhall Spa. It is plain therefore that in this locality O. dilatata is associated with, and almost takes the place of, that oyster. Passing towards the south, the brickyard west of West Brankwith, near Wragby, seems to be in this region from the multitude of fragments of oysters, showing the curving round of the band of similar strata to the S.E., and the low level in which the Langton pit is dug. To the south, again, at Hawkstead Hall (five miles south-west of Horncastle), a small pit exposes gypsiferous clays (the lower zone), with septarian and rather bituminous nodules. These contain, in abundance, a peculiar form of Amm. serratus (like Sowerby's original), with Belemnites nitidus and Ostrea deltoidea. The pit at Woodhall Spa, a mile to the south, is much more fossiliferous. Some of the large doggers are almost entirely composed of Serpula tetragona; others contain Avicula ædelignensis; while the clays are full of Ostrea deltoidea and Belemnites nitidus. There are beside: Ammonites serratus, Sow. Lima ædilignensis, Bla. Thracia depressa, Sow. It was from this pit probably that Sowerby's original specimens of Serpula tetragona came, as he mentions their filling whole blocks and being associated with Avicula inæquivalvis (ædilignensis) and Astarte (probably supracorallina), which latter species we ought therefore to add here to the list. It is a remarkable illustration of the persistency of these regions over considerable areas, that in South Yorkshire the Kimmeridge Clay seen has an exactly similar appearance to that at Woodhall Spa and Hawkstead Hall, and contains Amm. serratus of the Sowerbian form and Ostrea deltoidea at Elloughton; and near Leavening are also blocks filled with Serpula tetragona and numerous Bel. nitidus and Ostrea deltoidea, associated, however, with Amm. cordatus. Yet this is not the lowest region of the Kimmeridge Clay in Lincolnshire; for at Worlaby are met with sandy clays with very few fossils, the fauna being reduced to Lingula ovalis (abundant), Lucina, sp., and Amm. biplex. From their stratigraphical position they must lie below the last described, and are probably not far above the base of the formation. The exposure here is a very satisfactory one, from its proving, by the presence of Lingula ovalis, that it is still in Kimmeridge Clay; and therefore, of course, the beds above must be. This series of pits, again, make another well-marked subzone, characterized, as Mr. Judd noticed, by the abundance of Ostrea dilatata and Belemnites nitidus. No Rhynchonella inconstans, however, is reached; indeed I have never yet found it associated with Ammonites serratus. It is well known that the Coral Rag is absent from Lincolnshire, and the succeeding beds are those of Oxford Clay, which may be well seen with their characteristic fossils at Bardney and Langworthy. The different exposures of Lower Kimmeridge in Lincolnshire may be thus arranged in descending order : It is very difficult to estimate the total thickness represented by these various horizons; but as many of the pits themselves reach a depth of 30 ft., and there are eight stages, it cannot be less than 240 ft., supposing that every portion happened to be dug into at one place or another. A more probable estimate would be obtained by supposing each of these separate exposures to occupy a separate 30 feet, which would give 450 feet; but such estimates are entirely conjectural. Comparing now the Lower Kimmeridge of other counties with this typical development in Lincolnshire, I of course include the whole of the "Middle Kimmeridge of Filey Bay" of Mr. Judd in this division. It contains several of the characteristic fossils, with others that have not been met with in Lincolnshire, among which may especially be mentioned Exogyra virgula. A portion of his "Lower Kimmeridge" is also probably of this division. I have already stated that I regard the base of the pit at Ely as Lower Kimmeridge, partly on account of its more clayey character, but chiefly from its contained fossils, especially Ammonites serratus, A. longispinus, Arca rhomboidalis, Astarte ovata, Serpula tetragona, Avicula ædilignensis, Pecten Grenieri, Dentalium Quenstedti, and Lingula ovalis. Several other fossils are collected at this pit; but as this is the only pit I have seen in Cambridgeshire, they will appear in the general list. The great mass of the Kimmeridge Clay of the "inland counties" belongs to this lower division, which accounts for Professor Phillips saying that the upper portion is most fossiliferous-that is, the region of Market Rasen. I have not very carefully examined the clay in this range, as its fossils have been already collected and recorded, but only satisfied myself of its general accordance with the Lower Kimmeridge of Lincolnshire at Swindon and at Hartwell. The clay is far more sandy than anywhere in that county, and contains several fossils peculiar to the district. At the former place, after very little if any Upper Kimmeridge, several bands are seen in some large brick-pits now in full operation, and very fossiliferous. In the nearest but one to the railway occurs a strong band of limestone full of Amm. biplex, a feature not seen elsewhere; and the beds dip more than 20° to the S. The dark clay at the base of the next, in which great septarian doggers occur at the top, has many layers of compressed Thracia depressa, which reminds one of a similar abundance of this shell at Weymouth. Prof. Phillips mentions no fossils from the Kimmeridge Clay of Swindon in his list; nor can I find any account of them. Those that I found are the following, though there must be many more : Ichthyosaurus, sp. incurva, Bennett. Astarte supracorallina, D'Orb. Lucina substriata, Röm. -? balmensis, Cont. Cardium striatulum, Sow. Flambarti, Dollf. Exogyra virgula, Desh. To those recorded from Hartwell I have to add the following very characteristic forms : Q. J. G. S. No. 122. |