PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 411 



the Fisli Era, when the heterocercals, like the shark, were the 

 highest type. The third has been called the Reptilian Era, 

 when animals allied to the crocodile and lizard were the highest 

 type. The fourth has been called the Mammalian Era, when 

 animals allied to the elephant and rhinoceros were the highest 

 type. Succeeding this last era in the order of time, comes what 

 is termed the Drift Era, when all that portion of the American 

 continent east of the Missouri river, and as far south as the latitude 

 of New York city, was submerged beneath the waters of an ocean, 

 into which arctic currents brought ice and icebergs, transporting 

 rocks and gravel from the north. It was in this age that all the 

 beds of clay, gravel and sand, now found overlying the solid 

 rocks, were spread upon the earth's surface, over that portion of 

 the American continent above alluded to. During the continu- 

 ance of this period of submergence, it has been supposed that 

 all previously existing land animals were destroyed. It was 

 after the Drift Era, when the submerged earth came up above 

 the waters, and dry land appeared once more, that man made 

 his first appearance upon our planet. The evidence of this is 

 negative. It consists in the fact that neither his bones, nor any 

 of the works of his hands, have been found to any great depth 

 beneath the surface. In none of the deep-seated and consequently 

 the oldest rocks, have any of the remains of man, or any evidence 

 of his existence, been discovered. 



The remains of the human race, found in geological formations, 

 may be divided into two classes; first, his works ; and secondly, 

 his bones. His works consist of buried and ruined cities, such 

 asHerculaneum and Pompeii of Italy, and those found in Egypt 

 and Syria; dwellings, rudely constructed of stone, found in 

 Northern Europe and California ; .and implements of war, the 

 chase and husbandry, found buried deep in peat bogs, in caves, 

 or in gravel beds. Works of man have thus been found at con- 

 siderable depths, at Abbeville and Amiens, St. Anchieul, Cliafil- 

 lon sur Leine, and Oise, in the Department of Percy, in France. 

 In these localities, the rudely constructed flint implements of an 

 ancient race, are found associated with the bones of the elephant, 

 hippopotamus, rhinoceros, bear, lion, and hyena — animals now 

 extinct in Europe. * At L'Aubre, Department of Arcy, the frag- 

 ment of a human jaw, with teeth, was found with similar asso- 

 ciations. The rib-bone of the auroch, an extinct ox, was found, 

 apparently wounded by one of the flint implements. In England 



