Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 16, 2025
Some of the most ancient Silurian animals, as the Nautilus, Lingula, etc., do not differ much from living species; and it cannot on my theory be supposed, that these old species were the progenitors of all the species of the orders to which they belong, for they do not present characters in any degree intermediate between them.
This "lingula" rests upon a base of terra firma whose westernmost projection is Indian Point. From the latter runs northwards the "infamous" Indian Bar, compared by old sailors with a lengthened Bill of Portland; a reef some three miles long, which the waves assault with prodigious fury; a terror to slavers, especially in our autumn, when the squalls and storms begin.
In the mud close to the edge of the beach sand one of the most singular of marine animals exists, and often its empty, horny, flexible, semi-transparent shell, always tinted green, may be found. It is known in some works as LINGULA ANATINA, and by the natives of this Isle, by whom a certain part of it is eaten, as "Mill-ar-ing."
The Silurian Lingula differs but little from the living species of this genus; whereas most of the other Silurian Molluscs and all the Crustaceans have changed greatly. The productions of the land seem to change at a quicker rate than those of the sea, of which a striking instance has lately been observed in Switzerland.
The Tremadoc slates of Sedgwick are more than 1000 feet in thickness, and consist of dark earthy slates occurring near the little town of Tremadoc, situated on the north side of Cardigan Bay, in Carnarvonshire. Davis. The inferiority in position of these Lingula flags to the Tremadoc beds was at the same time established.
In like manner, it is the presence of such genera as Pyrula, Columbella, Terebra, Cassidaria, Pholadomya, Lingula, Discina, and others which give a southern aspect to the Coralline Crag shells.
Let it be borne in mind that Avicula, Mytilus, Chiton, Natica, Patella, Trochus, Discina, Orbicula, Lingula, Rhynchonella, and Nautilus, all of which are existing genera, are given without a doubt as Silurian in the last edition of "Siluria;" while the highest forms of the highest Cephalopods are represented in the Lias by a genus, Belemnoteuthis, which presents the closest relation to the existing Loligo.
The next subdivision of the Upper Ludlow consists of grey calcareous sandstone, or very commonly a micaceous stone, decomposing into soft mud, and contains, besides the shells mentioned above, Lingula cornea, Orthis orbicularis, a round variety of O. elegantula, Modiolopsis platyphylla, Grammysia cingulata, all characteristic of the Upper Ludlow.
Hicks and Salter, to whose exertions we owe almost all our knowledge of the fossils, have pointed out that the most characteristic genera found in them are quite unknown in the Lingula Flags, while they possess many of the strictly Lower Cambrian genera, such as Microdiscus and Paradoxides. David's. The beds are well exhibited in the neighbourhood of St.
Falconer has given a striking instance of a similar fact, for an existing crocodile is associated with many lost mammals and reptiles in the sub-Himalayan deposits. The Silurian Lingula differs but little from the living species of this genus; whereas most of the other Silurian Molluscs and all the Crustaceans have changed greatly.
Word Of The Day
Others Looking