NATURAL HISTORY. 
they also, have been brought under far more accu- 
rate and precise rules than those to which the older 
mineralogists were accustomed. Thus much by 
way of proem to our subject, taken in its most 
comprehensive sense ; which however, is usually 
and conveniently divided into, MINERALOGY, pro- 
perly so called, which has for its peculiar object, 
the characters, chemical, and external, of the dif- 
ferent minerals, and their scientific arrangement in 
the cabinet-—and GroLogy, whose object is, the 
rock structures, and minerals as they exist in masses ; 
and their different relations to each other. We shall 
attend to this distinction as far as it may be practi- 
cally useful to do sv; in either department, the 
student will find a rich, and varied, and very imper- 
fectly explored field for his exertions, in the district 
we are about to treat of, which will be prescribed 
within the fellowing tolerably well defined bounda- 
ries, in tracing which, as well as in following us 
thro’ the localities, and space occupied by the differ- 
ent formations, the map should be kept open before 
him.—A N. E. and S. W. line, drawn across the 
map, from Dartmeet, thro’ the parishes of Widdi- 
comb inthe Moor, Manaton, Lustleigh, Hennock, 
Christow, Doddiscombsleigh, Dunchideock, and 
ide, to Exeter, forms our Western boundary, and 
the Dart, the Exe, and the sea-coast included be- 
tween those rivers, the other three, Thus embracing 
within appropriate limits, all the strata of a much 
wider range; for an East and West line, from 
Dawlish, situated on the red sandstone formation, 
