414 Miscellanies. 



received some valuable contributions the present year. The sim- 

 ultaneous appearance of two considerable works devoted to the de- 

 scriptions of rocks and fossils, has not hitherto marked the American 

 history of this science. The other work alluded to, is Professor 

 Hitchcock's Geological Report of Massachusetts, whose author from= 

 the nature of his region has confined himself to the elucidation of non- 

 fossiliferous rocks, while Mr. Lea, has been led to investigate some of 

 the more recent, or semi-organic, formations : the former of these nat- 

 uralists having, as was fit, entered upon his researches through the 

 portals of mineralogy, while the latter has. made a no less felicitous 

 debvt as a conchologist. Mr. Lea's investigations, concerning our 

 fresh water shells, particularly the family of them denominated the 

 JVaiades has rendered his transition to the study of extinct shells as 

 easy, as we have no doubt it has been successful. Not that we are 

 prepared to vouch, that out of two hundred and fifty supposed species, 

 afforded by a single bluff, two hundred and nineteen are new, as Mr. 

 Lea supposes ; though better means than we at present possess, add- 

 ed to the well earned reputation of the author, must for the present 

 restrain us from calling in question so extraordinary a discovery. 



The following is Mr. Lea's table of contents ; viz. " Tertiary For- 

 mation of Alabama, New Tertiary Fossil Shells from Maryland and 

 New Jersey, New Genus of Fossil Shell from New Jersey, Tufa- 

 ceous Lacustrine Formation of Syracuse, Onondago County, New 

 York :" although it must be remarked, that about two hundred pages 

 are devoted to the first of these topics. 



The introduction embraces a rapid sketch of the developement 

 and occurrence of organic productions in the earth's strata. Omit- 

 ting his remarks upon the transition and secondary fossils, we com- 

 mence our extracts with his explanation of Mr. Lyell's denomination 

 of the three periods admitted by geologists to exist in the Tertiary ; 

 viz. the Pliocene period, the Miocene period, and the Eocene period. 



" The first is derived from the Greek words ttXsiwv major and xaivog 

 recens, as most of them are recent species and of course of later 

 deposit. This he subdivides into the Newer and Older Pliocene, in 

 which M. Deshayes, does not agree with him. The second Mio- 

 cene, is, from (xs/wv minor, and xaivos recens, there being here a mi- 

 nority of recent species. The third, the Eocene, is derived from 

 rjwff aurora, and xalvog recens, this being the dawn of the existing state 

 of the animate creation. 



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