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descend, says he, to examine microscopic shells, from their insignificant size: but we cease to think them insignificant, when we reflect that it is by means of the smallest objects, that Nature every where produces her most remarkable and astonishing phenomena. Whatever she may seem to lose in point of volume in the production of living bodies, is amply made up by the number of the individuals, which she multiplies with admirable promptitude to infinity. The remains of such minute animals have added much more to the mass of materials which compose the exterior crust of the globe, than the bones of Elephants, Hippopotami, and Whales.

CHARTER XVI.

Proofs of Design in the Structure of Fossil Articulated, Animals.

THE third grand division in Cuvier's arrangement of the animal kingdom, viz. the articulated animals, comprehends four classes.

1. The Annelidans, or worms with red blood.

2. Crustaceans, most familiar to us under the form of Crabs and Lobsters.

3. Arachnidans, or Spiders.

4. Insects.

SECTION I.

First Class of Articulated Animals.

FOSSIL ANNELIDANS.

HOWEVER numerous may have been the ancient species of Annelidans without a shelly covering, naked worms of this class can have left but slight traces of their existence, except the holes they perforated, and the little accumulations of sand or mud cast up at the orifice of these perforations; in a preceding chapter* we have noticed examples of this kind. We have also abundant evidence of the early and continued prevalence of that order of Annelidans, which formed shelly calcareous tubes, in the occurrence of fossil Serpulæ in nearly all formations, from the Transition periods to the present time.

SECTION II.

Second Class of Articulated Animals.

FOSSIL CRUSTACEANS.

THE history of fossil Crustaceans has been hitherto almost untouched by Palæontologists, and their relations to the existing Genera of this great Class of the Animal Kingdom are to olittle known to admit of discussion in this place.

See note at pages 198-199.

We may judge of their extent in certain Formations, from the fact, that in the cabinet of Count Munster, there are nearly sixty species collected from a single stratum of the Jurassic Limestone of Solenhofen. A rich harvest, therefore, remains in store for the Naturalist who will trace this interesting subject through the entire series of Geological formations.

The analogies between existing species, and certain fossil remains of Crustaceans have been beautifully illustrated by the investigations of M. Desmarest. From him we learn, that all the inequalities of the external shell in the living species have constant relation to distinct compartments in their internal organization. By the application of these distinctions to fossil species, he has pointed out a method of comparing them with living Crustaceans in a new and unexpected manner, and has established satisfactory analogies between the extinct and existing members of this very numerous Class, in cases where the legs and other parts on which generic distributions have been founded, were entirely wanting.*

* H. Von Meyer has recently noticed five or six extinct genera of Macrourous Decapods in the Muschelkalk of Germany. (Leonhardt and Bronn Jahrbuch, 1835.)

The subject of English fossil Astacids (Crawfishes) is at this time receiving important illustration in the able hands of Prof. Phillips.

In a recent communication to the Geological Society (June 10, 1835,) Mr. Broderip describes some very interesting remains of Crustaceans from the Lias at Lyme Regis, in the collection of Viscount Cole. In one of these, the Lamella of the external Antennæ, the form and situation of the eyes, and other characters, show that it was a macrourous decapod intermediate between Palinurus and the Shrimps.

A fragment of another macrourous decapod proves the existence at this early period of a crustacean approaching to Palinurus, and as large as our common Sea Crawfish.

Two other specimens exhibit the breathing organs of another delicate Crustacean, with the tips of the four larger and four smaller branchiæ preserved, and pointing towards the region of the heart, showing that these fossil Crustaceans belonged to the highest division of the Macroura. They

Referring my readers to these valuable commencements of the history of fossil Crustaceans, I proceed to select one very remarkable family, the Trilobites, and to devote to them that detailed consideration, to which they seem peculiarly entitled, from their apparently anomolous structure, and from the obscurity in which their history has been involved.

Trilobites.

The great extent to which Trilobites are distributed over the surface of the globe, and their numerical abundance in the places where they have been discovered, are remarkable features in their history; they occur at most distant points, both of the Northern and Southern Hemisphere. They have been found all over Northern Europe, and in numerous localities in North America; and in the Southern Hemisphere they occur in the Andes,* and at the Cape of Good Hope.

No Trilobites have yet been found in any strata more recent than the Carboniferous series; and no other Crustaceans, except three forms which are also Entomostracous, have been noticed in strata coeval with any of those that

reminded Mr. Broderip of the living Arctic forms of the macrourous decapods.

* I learn from Mr. Pentland that M. D'Orbigny has lately found Trilobites, accompanied by Strophomena and Producta in the Greywacke slate formation of the Eastern Cordillera of the Andes of Bolivia. Fresh-water shells, Melania, Melanopsis, and probable Anodon, occur also in the same rock; a fact which seems analogous to the recent discovery of similar fossils in the Transition rocks of Ireland, Germany, and the United States. The Fresh-water fossils occurred near Potosi, at an elevation of 13,200 feet.

M. D'Orbigny's specimens also confirm Mr. Pentland's view, as to the analogies between the great Limestone formation of this district, and the Carboniferous limestones of England; and as to the great extent also of the Red Marl, and New red sandstone formations on the Continent of South America.

contain the remains of Trilobites;* so that during the long periods that intervened between the deposition of the earliest fossiliferous strata and the termination of the Coal formation,† the Trilobites appear to have been the chief representatives of a class which was largely multiplied into other orders and families, after these earliest forms of marine Crustaceans became extinct.

The fossil remains of this family have long attracted attention, from their strange peculiarities of configuration. M. Brogniart, in his valuable History of Trilobites, 1822, enumerated five genera,‡ and seventeen species; other writers (Dalma, Wahlenberg, Dekay, and Green,) have added five more genera, and extended the number of species to fifty-two; examples of four of these genera are given in plate 46. Fossils of this family were long confounded with Insects, under the name of Entomolithus paradoxus; after many disputes respecting their true nature, their place has now been fixed in a separate section of the class Crustaceans, and although the entire family appears to have been annihilated at so early a period as the termination of the Carboniferous strata, they nevertheless present

* In Scotland two genera of Entomostra cous Crustaceans, the Eurypterus, and Cypris, occur in the Fresh-water limestone beneath the Mid Lothian Coal Field; the Eurypterus at Kirkton, near Bathgate, and the Cypris at Burdiehouse, near Edinburgh. (Trans. Royal Soc. Edin. vol. xiii.) The third Genus, Limulus, has but recently been recognised in the Coal Formation, and will be described presently. The Entomostracans appear to have been the only representatives of the Class Crustaceans until after the deposition of the Carboniferous strata.

↑ Trilobites of a new species have lately been found in Ironstone from the centre of the coal measures in Coalbrook-dale. Lond. and Edin. Phil. Mag. vol. 4. 1834, p. 376.

The names of these Genera are Calymene, Asaphus, Ogyges, Paradoxus, and Agnostus. Some of these terms are devised expressly to denote the obscure nature of the bodies to which they are attached; e. g. Asaphus, from araons, obscure; Calymene, from xxxvμ, concealed; apudcies, wonderful; ava ros, unknown.

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