Lesley.] 494 • [XovemborG. 



habits ; but when on shore it must have walked in a measure 

 erect, like strathous birds, or have leaped like the batrachians. 

 When feeding- it must have made a tripod of its hind legs and 

 tail, grasping with its short forelegs the branches, on the leaves 

 or fruit of whicli it browsed, of some kind of evergreen ; for all 

 the specimens of wood found embedded with it proved, on 

 microscopic examination, to be coniferous. How its carcass 

 came to lie upon a bed of shells, interspersed with these chunks 

 of wood, is hard to explain. The shells were of forty-two dif- 

 ferent species, and some of them so fragile and yet so unin- 

 jured, the most tender and delicate forms showing no trace 

 of abrasion, and the two valves of all the bivalves being still 

 together, that the water in which they lived must have been 

 either perfectly protected from the winds, or else profoundly 

 deep. The marl itself is sufficient evidence of the stoppage of 

 all the currents carrying sand. We might therefore suppose 

 a bog — or lagoon — or ai'chipelago deposit. But this suppo- 

 sition is opposed by the great geographical extent of the Mid- 

 dle Cretaceous Formation, from New York to New Oideans and 

 Cairo ; and by the uniform composition of the mineral, and uni- 

 form thickness of the stratum. 



It remains then to determine the limits of the ocean in 

 which, and the direction of the muddy current by which it was 

 deposited. The investigation of this question has never to m}' 

 knowledge been undertaken. Instead of that, an undue degree 

 of attention has been bestowed upon the question of mere age. 

 Vanuxem, Morton, Rogers, Tuomey, Hall, Meek, Hayden, Mar- 

 cou, Cooke, L^'ell, D'Orbigny, Mantell, are all in turn cited by 

 Mr. Lea, as expressing discordant opinions in attempting a cor- 

 relation of tlie Green Sand marls of our side, with the Lower, 

 Middle or Upper Green Sand of the other side of the Athxntic, 

 by means of the imbedded forms of animal life. Now recent in- 

 vestigations into the Cretaceous and Tertiary Formations of the 

 West, — investigations still continued on the largest scale, — 

 teach us how little value is to be set on fossils, whether animal 

 or vegetable, especially vegetable, as indicators of precise con- 

 temporaneity. They show how the principle of life has pursued 

 its route of development through a normal series of forms, at 

 different rates on distant continents, and in separate water 

 basins ; one region out-stripping another in the I)ar\Yinian race ; 



