tire fusion and ultimate change of the original strata into crystalline trap ; so that, here also, the lignites have equally escaped. Even however if lignite should be found sur rounded by a crystalline trap, it does not follow that the rock has not been in a state of fusion, or at least of softness, sufficient to enable its parts to assume a crystalline character. The siliceous schists beneath basalt often assume that concretionary structure which proves a softened condition of the same nature ; and, in such cases, shells are often found entangled in the mass, sometimes deformed by pressure, as the lignites themselves are, yet retaining their integrity, with much of their original characters. Neither is the bitumi nous matter of the strata dissipated in such cases ; since, the associated limestones and shales are often highly bituminous. Charcoal also, I need not say, is indestructible by heat, when protected from air ; and though sometimes altered in chemical character by the loss of its hydrogen, it still retains its form. Hence then, even the woody lignites might remain surrounded by fluid trap till it had cooled, as coal also unquestionably does, where the ordinary coal strata are found in similar circumstances. If this par ticular case has not occurred in trap, it is known to have happened with lava, so that the difficulty is com pletely removed. In Italy, trees have been found en tangled in perfect lavas, having burnt out where there was access of air; and in the isle of Bourbon, the trunks of palms have thus also been observed wrapped in lava; the stony matter having further pene trated the fissures so as to have assumed their shapes. Hence then might the lignites of trap often preserve their vegetable organic character, together with their chemical nature, in considerable perfection; while, in other cases, they might he entirely converted into