The Bone-Cabin Quarry deposit represents entirely different conditions. The theory that it is the accumulation of a flood is, in my opinion, improbable, because a flood would tend to bring entire skeletons down together, distribute them widely, and bury them rapidly. A more likely theory is that this was the area of an old river-bar, which in its shallow waters arrested the more or less decomposed and scattered carcasses which had slowly drifted down-stream toward it, including a great variety of dinosaurs, crocodiles, and turtles, collected from many points up-stream. Thus were brought together the animals of a whole region, a fact which vastly enhances the interest of this deposit. _The Giant Herbivorous Dinosaurs._ By far the most imposing of these animals are those which may be popularly designated as the great or giant dinosaurs. The name, derived from _deinos_ terrible, and _sauros_ lizard, refers to the fact that they appeared externally like enormous lizards, with very long limbs, necks, and tails. They were actually remotely related to the tuatera lizard of New Zealand, and still more remotely to the true lizards. No land animals have ever approached these giant dinosaurs in size, and naturally the first point of interest is the architecture of the skeleton. The backbone is indeed a marvel. The fitness of the construction consists, like that of the American truss-bridge, in attaining the maximum of strength with the minimum of weight. It is brought about by dispensing with every cubic millimeter of bone which can be spared without weakening the vertebrae for the various stresses and strains to which they were subjected, and these must have been tremendous in an animal from sixty to seventy feet in length. The bodies of the vertebrae are of hour-glass shape, with great lateral and interior cavities; the arches are constructed on the T-iron principle of the modern bridge-builder, the back spines are tubular, the interior is spongy, these devices being employed in great variety, and constituting a mechanical triumph of size, lightness, and strength combined. Comparing a great chambered dinosaurian (_Camarasaurus_) vertebra (see above) with the weight per cubic inch of an ostrich vertebra, we reach the astonishing conclusion that it weighed only twenty-one pounds, or half the weight of a whale vertebra of the same bulk. The skeleton of a whale seventy-four feet in length has recently been found by Mr. F.A. Lucas of the Brooklyn Museum to weigh seventeen thousand nine hundred and twenty pounds. The skeleton of a dinosaur of the same length may be roughly estimated as not exceeding ten thousand pounds.