Now, it is not accordant with our apprehensions that trap is ever at the present time employed to designate a _simple mineral_, nor has Professor Cleaveland himself used it in his tabular view, or in his description of simple minerals. In our view, it is the _classical_ word of modern geology, to designate that description of rocks in which hornblende predominates, and perhaps a few others of minor importance usually associated with them. It is true, a rock composed of pure hornblende may be called trap, but it is not true, _vice versa_, that this rock, considered in its character of a simple mineral, is called trap. If our views are correct, the section which is headed _trap_ or _hornblende_, should be _trap_ or _hornblende rocks_, and greenstone should come in as a subdivision, and not form a distinct section. With these alterations, and with the substitution of rock in the _first_, and rocks in the _second_ instance, in the paragraph above quoted, instead of _mineral_ and _minerals_, we apprehend the view of this family of rocks would be much more clear, and a degree of confusion, which learners now experience from the paragraph, would be prevented. If we are wrong, we are sure Professor Cleaveland will pardon us; if right, his candour will readily admit the correction. As to the manner in which the work of Professor Cleaveland is executed, the remarks which we already made, have in a good degree anticipated this head. We cannot, however, dismiss the subject without adding that, in our opinion, this work does honour to our country, and will greatly promote the knowledge of mineralogy and geology, besides aiding in the great work of disseminating a taste for science generally. Our views of the plan we have already detailed. The manner of execution is masterly. Discrimination, perspicuity, judicious selection of characters and facts, and a style chaste, manly, and comprehensive, are among the characteristics of Professor Cleaveland's performance. It has brought within the reach of the American student the excellencies of Kirwan, Jameson, Haüy, Brochant, Brongniart, and Werner; and we are not ashamed to have this work compared with their productions. In our opinion Professor Cleaveland's work ought to be introduced into all our schools of mineralogy, and to be the travelling companion of every American mineralogist. We trust that all cultivators of mineralogy and geology in this country, will willingly aid Professor Cleaveland in enlarging his list of American localities for a second edition; and we hope that he will repay them, at a future day, by giving us a distinct treatise on geology, with as particular a delineation as possible of the geological relations of the great North American formations. Mr. Maclure has, with great ability, sketched the outline; but much labour is still needed in filling up the detail. ART. III. _New Locality of Fluor Spar, or Fluat of Lime and of Galena, or Sulphuret of Lead._