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 anomalous 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 local ties in North America; and in the Southern Hemisphere they occur in the Andes,[1] 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
They 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. Freshwater shells, Melania, Melanopsis, and probably 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 Freshwater 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.
