76 Dr Boue’s Observations on M. Beudant's Opinions 
amygdaloidal masses in particular, one may be inclined not to 
look upon them as scorified infiltrated parts, because their limits 
with basalts are sometimes pretty decisively marked for a short 
space ; but if this limit be followed, one soon becomes aware of 
their true nature. This is evidently exemplified every year by 
Professor Jameson in his practical illustrations of geology along 
the Fife coast, a locality which, together with that pf Prague, I 
would earnestly recommend to the study of M. Beudant. 
This idea once admitted, it will no longer appear so singular 
for] M. Beudant to see amygdaloids in connection with por- 
phyries, to observe these rocks in an earthy state, and to be 
obliged to suppose them every where decomposed in the same 
way. Indeed, why should this alteration be different in different 
places ? Would not this be contrary to nature ? And do not 
the lavas undergo d^lteration, especially in their porous and sco- 
riaceous parts.? Is it, besides, well demonstrated, that these 
wackes, or the bases of these amygdaloids, always owe their 
earthy nature simply to an alteration ? and have we not, on the 
contrary, some facts, which would tend to show that this nature 
depends, in some measure at least, upon their primitive state, I 
mean upon the matters which gave rise to these products ? 
We see that it is by no means impossible to make the pro- 
posed difficulties vanish ; and one perceives with pleasure, that, 
notwithstanding all this, the same geologist admits not only the 
great similarity of amygdaloids and infiltrated basalts, but also 
that of the minerals disseminated in both rocks. 
Resuming a comparative view of the facts and arguments ad- 
duced, it will now seem clear to every impartial mind, 1^^, That 
the mineralogical analogy of some varieties of secondary pitch- 
stones to some others of volcanic pearlstone and pitchstone, and 
the presence even of only small masses of scoriaceous parts in 
the older pitch stones, are proofs of the igneous origin of these 
last ; and that, on the contrary, their aqueous formation can be 
supported by no mineralogical proof whatever, deduced from 
what is clearly known respecting them. 
That the presence of scoriaceous parts in porphyry and 
greenstone deposites, the local formations of porphyries entirely 
analogous to volcanic products, and their decided separation 
from the aqueous or mechanico-chemical deposites, show most 
