Hides and Misrules in Classijication. — Marcov. 35 
For that same and ff)r tlie range of the Maclurea, Receplaeu- 
lites et al. we have not suttieientl}^ full explanation. To un- 
derstand the history of the physical changes and faunal mi- 
grations in this area, will no doubt be the surest means for 
explaining in a satisfactory manner tlie relations to the type 
Trenton and Hudson. For the present, correlations into dis- 
tricts into which we cannot trace the beds by stratigrap'hic 
continuity, are to be assumed with caution, prompted by our 
knowledge that quite recentl}^ we have not befen entirely suc- 
cessful in correlating not distantly separated sections of the 
Galena and Maquoketa series b}' tiie lithological and paleon- 
tological methods. 
RULES AND MISRULES IN STR ATIGRAPHIC 
CLASSIFICATION. 
By Jules Marcou, Cambridge, Mass. 
I. 
CONTENTS. 
Page. 
Giraud-Soulavie.— William Smith. — Alex. Brong-niart ;1t 
Classification of the Niagara with the 01<1 Red Sandstone 38 
Clasfiiflcation of the Taconic with the Hudson River 38 
The Georgia formation or Elliptocephalus zone 39 
Phillipsburgh and Pointe-Levis formation 43 
Geology of (^hazy village 4C 
Geology of Shoreham (Vermont) 49 
Girand-Soiilavie. — William Smith. — Alexandre Brongniart. 
At first the great stratigraphic classitications were made 
according to some great area of geological distribution of 
rocks having the same petrography, or at least having a cer- 
tain similitude as regard the lithology and the colors of the 
main strata; such as the chalk, the Red Sandstone, the Jura 
limestone, the slate, the carbon or coal. Great breaks and 
discordance of stratification were also used, as well as trans- 
gression and retrogression of the strata. And according to 
those simple and most striking rules easily recognized in prac- 
tical geology, the strata were divided into the Primarj^ tlie 
Transition, the Secondary, and the Tertiary periods or great 
systems, and into the Grauwake, the Old Red sandstone, the 
Carboniferous, the New Red sandstone, the Lias, the Jura 
limestone, the Cretaceous, the Calcaire grossier. etc. 
Then came the "medals of creation," or fossil organic re- 
mains. The first who recognized that fossils differed accord- 
