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 
début as a conchologist. Mr. Lea’s investigations, concerning our 
fresh water shells, particularly the family of them denominated the 
‘Naiades 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 xiv major and xaiwog 
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 ys/uv minor, and xouveg recens, there being here a:mi- 
nority of recent species. The third, the Eocene, is derived from 
jwe aurora, and xaivos recens, this being the dawn of the existing. state 
of the animate creation. 
