Europe as the subject of the map because it contained a great area, practically well known, the largest number of geologists, and included the greatest number of cartographical difficulties. Containing the largest number of geologists, representing many nationalities, it was conceded that any map which could pass their acceptance would stand any test of criticism elsewhere. The inherent puzzles of structure in Europe furnished a fascinating series of difficult problems for solution, long and zealously discussed, with both natural and artificial intricacies. No better area to test the patience and tax the genius of the congress could have been chosen. The committee appointed to prepare the map comprised Messrs. Beyrich and Hauchecorne, of Germany, with power of direction at Berlin; Prof. Renevier, of Switzerland, as general secretary; Messrs. Daubrée, of France; Giordano, of Italy; A. Karpinsky, of Russia; Mojsisovics, of Austria-Hungary; and Topley, of Great Britain. Professors Daubrée, Giordano, and Topley have since died. The scale of the map is one in one million and a half. It is divided into forty-nine sheets of 18·89 by 20·86 inches. These sheets, when all are completed, will form a rectangle 11·04 feet high by 12·17 feet wide. The topographic base was prepared by Prof. Kiepert, of Berlin. D. Reimer & Co., Berlin, are the pub-