From the foregoing, which are among a great collection of accepted data, it will be seen that, in whatever quarter of the world salt lakes occur, the same characteristics are encountered, viz., salt depositing on mud and covered by mud. Every shower of rain creates a certain amount of mud or sand, and every brook and stream running into the salt lakes during the rainy season brings in a certain quantity of the same material. The mud represents the wet season of the year, and the salt the dry season. The geological conditions must have been the same when salt was deposited in Cheshire, and with the instances of modern salt-forming regions before us, and the strata of the Cheshire salt country to guide us, it must be concluded that the genesis of rock-salt, modified by local circumstances, must have been the same in every case. Indeed, in the face of the evidence, it seems certain that the Cheshire beds of rock-salt have been crystallized out of the saturated waters of salt lakes, and that their admixture of marl has been caused by streams running into the lakes during the wet seasons, and that the peculiar amorphous mixture of marl and salt known as rock-salt is the result of the continual growth of pure salt crystals, and their partial destruction by mud-bearing fresh waters. This conclusion on the subject, which is now generally accepted, is based on the theory that the Cheshire salt lake was situated in a desert, or more probably a salty _steppe_, such as are found in the region of the Caspian Sea, and that the climate was divided into wet and dry seasons. The presence of rock-salt supports these ideas, because the marls could only be formed in periods of heavy rainfall, and the salt could only crystallize out in dry, water-evaporating periods. It is further evident that the lake, though extensive in area, was shallow, and that the dry seasons produced extensive shrinkages and caused salt to form in the saturated water that remained in the deeper parts, while the occurrence of the deep deposits in a shallow lake is explained by the constantly varying elevation and depression of the earth’s surface. The difficulty of explaining how the salt in this lake could be renewed to enable the waters to go on depositing for a geologic age is recognized, but it is no greater than that which is presented by scores of existing salt lakes out of which thousands of tons of salt are taken annually without causing any apparent diminution in the salt which forms year by year. And when it is considered that, in a lake having a probable area of from 500 to 1,000 square miles, the known salt deposits do not occupy 50 square miles, and in many portions contain 50 per cent. of marl, the difficulty does not seem to be insuperable. It is, moreover, safe to conclude that, when the bar rose that eventually cut off the Cheshire lake from the sea, it would be many years before the high tides ceased to wash over it and replenish the lake, and Dr.