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Show ERA OF THE NE'V RED SANDSTONE tysomus, &c., have been applied, vanish, and henceforth appear no more. . The third oToup, chiefly sandstones, vanously.colo~ed accordin,r to the amount and nature of the metallic oxide infused i~to them shows a recunence of agitation, and a consequent diminution of the .amount of animal life. In the upper part, however, of th1s group,. t.here are abund~nt symptoms of a revival of proper condihons for such hf?· There are marl beds the oricrin of which substance In decomposed shells i~ obvious; and in Germany, th.o~gh not in England, here occurs the musch_elkalk, containing numeroHs oro-anic remains (generally d1fferent from thos~ of the mao-neb sian limestone,) and noted for t h e.spec1. mens of land ar~mals, which it is the first to present 1n any consirlerable abundance to our notice. These animals are of the vertebrate sub-kingdom, but of its lowest class next after fishes-namely, reptiles-a portion of the terrestrial tnbes whose imp~rfect respiratory "ystem, perh::ps, fit.ted them fm: enduring an a_tmos~ phere not yet quite suitable for buds or maf!lrnifers. The Rpecinlens found in the muschelkalk are alhed .to the crocodile and lizard tribes of the present day, but In the latter instance are upon a scale of !Dagnitude as much superior to present forms as the lepidodendron of the .coal era was superior to the dwarf club-moss.es. ~f our tJme. These saurians also combine some pecuhanhes of struc~ ture of a most extraordinary character. The animal to which the name ichthyosaurus has been given was as lono- as a young ·whale, and it was fitted for livin,; in the wat~r thouo-h breathing the atmosphere. It had the vertebral c~lumn °and general bodily form of a fis~, but to that were added the head and breast-bone of a lizard, and the paddles of the w?ale tribes. The beak, moreover, was that of a porpOise, and the teeth w~re thos~ of a crocodile. It must have been a most destructive creature to the fish of those early seas. . . The plesiosau1·us was of similar bulk, with~ turtle-like body and paddle:;, showin~ that the sea :vas. Its ~lement, but with a long serpent-like neck, terrnmahng I!l a.saurian hcac1 calcnl a ted to reach prey at a considei able • The im~euiate cffec.ts of the slow respiration of the rct;>tilia, are, a low temperature in their bodi<'s, and a slow c~nsu~pt~on ~~ fond. Requiring little oxygen, th~y could have ex1sted m. an ~d mosphere containing a less proportion of that gas to carbonrc a gas than what now obtains. ERA OF THE NEW RED SANDSTONE. distance. These two animals, of which many varietie have been discovered, constituting distinct species, are supposed to have lived 1n the sl~allow borde~s of. the eas of- this and suosequent fN·mahons, devounng unmense quantities of the finny tribes. I.t w:1s at fir::;t thou~h~ th~t no c1·eatures approaching them In character now Inuahit the earth; but latterly Mr. Darwin h:1s discovered in the reptile-peopled Galapagos Islands, in the South Sea, a mal'ine saurian from three to four feet long. The megalosaurus was an enormous lizard-a land creature, also carnivorous. The pterodactyle was another lizard, but furnished with wings to pursue its prey in the air, and varying in size between a cormorant and a snipe. Crocodiles abounded, and some of these were herbivorou . Such was the iguanodon, a creature of the character of the inguana of the Ganges, but reaching a hundred feet in length, or twenty times that of its modern representative. There were also numerous tortoises, some of them reaching a great size ; and Professor Owen has found in 'Varwickshire some remains of an animal of the batrachian order,~ to which, from the pecular form of the teeth, he has .given the name of labyrinthidon. Thus, three of Cuvier's four ordei·s of reptilia (sauria, chelonia, and batrachia) ai:e. repre.sented in this formation, the serpent order (oph~dta) be1ng alone \\"anting The var1egated marl .beds which constitute the uppermost group o~ the formatwn, present two additional enera of hu$e. sa~nans-the phytosaurus and mastodon auru . It IS Ill the Upper beds of the reu sandstone that bed~ of salt first occur. These are sometitnes of uch thickness, that the ~ine from which the material ha been e~·cavated loo.ks like a lofty church. We see in the pre en*' 'Yorld no cucumstances calculated to produce the formabon of a bed of rock salt; yet it is not difficult to understand hovv: much strata were formed in an age marked by ultra-tropwal heat and frequent volcanic disturbance~ An estuary, cut off by an upthrow of trap, or a chan(J'e of lev:el, and left to dry up und~r the heat of the un ""·ould qmckly become the bed of a dense layer of rock 'alt second ~hift. of level, or some other volcanic disturba~ce fonnfctJ ng It again with the sea, would expose this tra: um. o b~Ing. covered over with a b.yer of sand or xnud destined In time to form the n8xt stratum of rock above it' .,. The order to which frogs and toads belong |
