Identifier: outlinesofcompar00agas (find matches)
Title: Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges
Year: 1870 (1870s)
Authors: Agassiz, Louis, 1807-1873 Gould, Augustus A. (Augustus Addison), 1805-1866 Wright, Thomas, 1809-1884
Subjects: Physiology, Comparative Zoology
Publisher: London : Bell & Daldy
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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-asa. 402 GEOLOGICAL SUCCESSION OF ANIMALS. conclude that the climate was much more uniform than atthe present day. Among the aquatic population, no soundwas heard. All creation was then silent. § 670. THE SECONDARY AGE. Reign of Reptiles.—TheSecondary age displays a greater variety of animals as well asplants. The fantastic forms of the palaeozoic age disappear,and in their place we see a greater symmetry of shape. Theadvance is particularly marked in the series of vertebrata.Fishes and a few reptiles are no longer the sole representativesof that department. Reptiles, birds, and mammals succes-sively make their appearance, but reptiles preponderate, par-ticularly in the Oolitic formation ; on which account we havecalled this age the Reign of Reptiles. § 671. The Carboniferous formation is the most ancient ofthe Secondary age. Its fauna bears, in various respects, aclose analogy to that of the palaeozoic epoch, especially inits Trilobites and mollusca.* Besides these, we meet here
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b a f ft d C y Fig. 381.—The Flora of the coal period. a Arborescent fern. d Neuropteris. g Araucaria. b Pecopteris. c Asterophyllites. i e Lepidodendron./ Calamites. k h Casuerina. This circumstance has caused the coal-measures to be generally referred AGES OF NATTJBE. 403 vrith air-breathing animals, as insects, scorpions, and rep-tiles. At the same time, land-plants first make their ap-pearance, namely, ferns of great size, club-mosses, and otherfossil plants. Fig. 381 exhibits some of the most typicalforms of the flora of this period. This abundant vegetationcorroborates what has been already said concerning the inti-mate connection existing between the animals and the land-plants of all epochs. The class of crustaceans has also improvedduring the coal period. It is no longer composed exclusivelyof Trilobites, but the type of horse-shoe crabs also appears,with other gigantic forms. Some of the mollusca, particularlythe bivalves, seem also to approach those of the Oolitic period.

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