neighborhood of Linlithgow I have derived for my collection pieces of carbonized wood in so complete a state of keeping, that under the microscope they exhibit unbroken all the characteristic reticulations of the coniferae of the Coal Measures. I descended the hill, and, after joining my friends at Strathpeffer,--Buchubai Hormazdji among the rest,--visited the Spa, in the company of my old friend the minister of Alness. The thorough identity of the powerful effluvium that fills the pump-room with that of a muddy sea-bottom laid bare in warm weather by the tide, is to the dweller on the sea-coast very striking. It _is_ identity,--not mere resemblance. In most cases the organic substances undergo great changes in the bowels of the earth. The animal matter of the Caithness ichthyolites exists, for instance, as a hard, black, insoluble bitumen, which I have used oftener than once as sealing-wax; the vegetable mould of the Coal Measures has been converted into a fire-clay, so altered in the organic pabulum, animal and vegetable, whence it derived its fertility, that, even when laid open for years to the meliorating effects of the weather and the visits of the winged seeds, it will not be found bearing a single spike or leaf of green. But here, in smell, at least, that ancient mud, swum over by the Diplopterus and the Diplacanthus, and in which the Coccosteus and Pterichthys burrowed, has undergone no change. The soft ooze has become solid rock, but its odoriferous qualities have remained unaltered. I next visited an excavation a few hundred yards on the upper side of the pump-room, in which the gray fetid breccia of the Strath has been quarried for dyke-building, and examined the rock with some degree of care, without, however, detecting in it a single plate or scale. Lying over that Conglomerate member of the system which, rising high in the Knock Farril range, forms the southern boundary of the valley, it occupies the place of the lower ichthyolitic bed, so rich in organisms in various other parts of the country; but here the bed, after it had been deposited in thin horizontal laminae, and had hardened into stone, seems to have been broken up, by some violent movement, into minute sharp-edged fragments, that, without wear or attrition, were again consolidated into the breccia which it now forms. And its ichthyolites, if not previously absorbed, were probably destroyed in the convulsion. Detached scales and spines, however, if carefully sought for in the various openings of the valley, might still be found in the original laminae of the fragments. They must have been amazingly abundant in it once; for so largely saturated is the rock with the organic matter into which they have been resolved, that, when struck by the hammer, the impalpable dust set loose sensibly affects the organs of taste, and appeals very strongly to those of smell. It is through this saturated rock that the mineral springs take their course.