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Scales of Aechmodus Leachii. c. The fossil fish, of which there are no less than 117 species known as British, resemble generically those of the Oolite, but differ, according to M. Agassiz, from those of the Cretaceous period. Hybodus reticulatus, Agassiz. Lias, Lyme Regis. a. Part of fin, commonly called Ichthyodorulite. b. Chimaera monstrosa.
Some are of opinion that the two plates have been the gizzard of a cephalopod; others, that it may have formed a bivalve operculum of the same. Skeleton of Pterodactylus crassirostris. Oolite of Pappenheim, near Solenhofen. a. The celebrated lithographic stone of Solenhofen in Bavaria, appears to be of intermediate age between the Kimmeridge clay and the Coral Rag, presently to be described.
The mammalia next in antiquity, of which we have any cognisance, are those of the Upper Oolite of Purbeck, discovered between the years 1854 and 1857, and comprising no less than fourteen species, referable to eight or nine genera; one of them, Plagiaulax, considered by Dr. Falconer to have been a herbivorous marsupial.
How much later, it is not so easy to declare, although probably they are not newer than the beginning of the Permian period, as no tin lodes have been discovered in any red sandstone which overlies the coal in the south-west of England. There are lead veins in Glamorganshire which enter the lias, and others near Frome, in Somersetshire, which have been traced into the Inferior Oolite.
The Collyweston beds, on the whole, assume a much more marine character than the Stonesfield slate. Hemitelites Brownii, Goepp. Syn. Phlebopteris contigua, Lind. and Hutt. Lower carbonaceous strata, Inferior Oolite shales.
Cassian Beds to the Triassic Periods. Discovery of new organic Types. Feathered Archaeopteryx of the Oolite.
Although the name of Coral Rag has been appropriated, as we have seen, to a member of the Middle Oolite before described, some portions of the Lower Oolite are equally entitled in many places to be called coralline limestones. Apiocrinites rotundus, or Pear Encrinite; Miller. Fossil at Bradford, Wilts. a. Stem of Apiocrinites, and one of the articulations, natural size. b.
The upper division of this series, which is more extensive than the preceding or Middle Oolite, is called in England the Cornbrash, as being a brashy, easily broken rock, good for corn land. It consists of clays and calcareous sandstones, which pass downward into the Forest Marble, an argillaceous limestone, abounding in marine fossils.
Proofs of a similar cementing action are seen in a rock at Kelloway, in Wiltshire. A peculiar band of sandy strata belonging to the group called Oolite by geologists may be traced through several counties, the sand being for the most part loose and unconsolidated, but becoming stony near Kelloway.
"It was always spoken of as a charm," though its ancient maker may have intended it for some prosaic practical use. I take the next example that comes to hand. "Thin flat oolite stones, having a natural perforation, are found in abundance on the Yorkshire coast. They are termed "witch stones," and are tied to door keys, or suspended by a string behind the cottage door, "to keep witches out."
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