This mighty tree belongs exclusively to the foggy regions of the Coast Ranges and the underlying metamorphic sandstone, for wherever either of these conditions is wanting, this tree does not exist. From the northern boundary line of the State down to the head of Tomales Bay it forms a continual forest, increasing in width northward. At Tomales Bay the chain is interrupted by a small bed of lime-rock. The interruption extending from the lower foot-hills of Tamalpais down to Belmont, is undoubtedly owing to the lowness of the hills. A connecting link is found, however, on the Oakland hills. That grove of redwoods, now almost entirely destroyed, affords the strongest evidences of the dependency of that species on the prevalence of heavy mists. From Belmont to a few miles below Santa Cruz is another narrow continuous chain, occupying mainly the leesides of the most western ranges and the deeper gulches eastward. From near the mouth of Salinas River to the head of Carmelo Valley, another long interruption is caused by a bituminous slate. The absence of redwood in this long interval can hardly be ascribed to any other cause, for it is known that Monterey and the adjacent regions are subject to heavier fogs than Santa Cruz. _Pinus insignis_ and _Cupressus macrocarpa_ occupy here those portions naturally belonging to the redwood and _Tsuga Douglasii_. Further south, from the head of Carmelo Valley to San Luis Obispo, the most southern limit, redwood occurs but sparingly, forming nowhere extensive groves. Associated with the redwood we find _Tsuga Douglasii_, a tree of a wide range, _Torreya Californica_, _Arbutus Menziesii_, _Quercus densiflora_, and in Mendocino County _Abies grandis_ Dougl. There are also some shrubs and herbaceous plants truly characteristic to them, the shrubs increasing as underwood northward, belong mostly to the Ericaceous family. It is a noteworthy fact that the arborescent growth of the leeside of the first range of hills generally consists, almost exclusively, of _Tsuga Douglasii_, and that this tree forms the outskirt east and particularly westward. In Mendocino County _Abies grandis_ unites with it for the same cause; there both trees form a dense belt, facing the ocean, and are encroaching fast on the redwood. In fact, the western portion of those redwoods show this encroachment most strikingly by a total absence of young redwood, and a dense, almost impenetrable, undergrowth of the two-mentioned species. The order of things is, however, reversed wherever the redwood has been cut. Its roots are imperishable, and as soon as the tree is cut they sprout and cover the soil rapidly to the exclusion of every other species—none being of so rapid a growth. The indestructibility of the roots prevents the clearing of such