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and less with reference to the supposed similarity of faunas and deposits with other and particularly European horizons.

The difficulties in the way of extended correlation are so great that for purposes of study it is often necessary to apply local names to the several formations of a particular district. There are, beyond a doubt, objections to the multiplication of names of geological horizons and already accepted terms should be employed as far as possible, but very frequently they prove to be inadequate for stratigraphical requirements. Such is the case in the New Jersey area.

Outside of the major divisions of the geological column it is impossible to employ the terms of European authors. All such attempts have, upon critical examination, failed to stand the test. The lithological and faunal characteristics show such wide variations that definite correlations of minor horizons are impossible. The geological formations of America must be studied first upon their own merits and only after a complete understanding of them has been gained can satisfacory comparisons be made with foreign areas. A detailed correlation of the New Jersey formations with European will therefore not be attempted.

Again the conditions under which the strata of the different portions of this country were deposited, are so varied that the same terms are not applicable over wide areas. The formations of the Interior are in a marked degree dissimilar from those of the Atlantic border, and even throughout the coastal plain very considerable differences are found in its various portions. Correlations of more satisfactory character can be made here than with foreign areas, but many obstacles debar the geologist from the full consummation of his task. It is possible to show in a general way the equivalency of the deposits upon the Atlantic border with those in the Gulf, the Interior, or on the Pacific coast, although in the case of individual formations such comparisons are of doubtful character.

Dr. White^[1] in his admirable essay upon the Cretaceous of North America, discusses very critically the evidence for the