NATURAL HISTORY. 
low the junction of that rock with the transition dis- 
tricts, the Trap must occur towards the lower part of 
the sand stone series ; from its alternating however 
with the latter, it would appear to be associated 
with 2 rather than with the transition series, as 
might otherwise have been supposed; more accu- 
rate examination may probably present instances 
of the rock along the lines of junction still more 
southernly than those noted, and enable this ques- 
tion to be settled with more certainty. The Rev. 
J, J. Conybeare has given a full and accurate 
account of the constituent parts and structure of 
it, which we shall here quote. ‘* The general as- 
pect of this reck, is that of a granular mass, some- 
what loosely compacted, mostly of a brown or pur- 
plish-brown, (which colour it probably owes to 
the oxide of Manganese.) In this are intermixed 
small portions of calcareous spar, mica, or chlorite 
and indurated clay (Lithomarge,) in quantities often 
forming a considerable part of the whole mass ; the 
Calcareous spar as well as the Manganese often tra- 
verses the rock im small veins; the eells of the 
amygdaloidal portion are filled or lined with brown 
oxide of manganese, ealcareous spar, and a coarse 
jasper ; this abundant admixture of substances ap- 
parently adventitious obscures the character of the 
rock, so as to make it difficult to pronounce with 
any certamty as to its essential eonstituents. These 
may probably be granular or earthy felspar, and 
one or more of the following—Hornblende—Au- 
gite—Bronzite—or Hyperstene—probably the se~ 
