This is the fact with the clay slate of the Woodbridge hills, near New-Haven, which is primitive; that of Rhode-Island, with anthracite, is transition; and that at Middlefields, west of Middletown, with impressions of fish, is secondary. Slate then appears to belong to all these three great classes of rocks. As to the _metalliferous_ limestone, we do not so much object to the introduction of this term by Bakewell, although it appears to us quite as well to say that certain limestones, those of the transition class for example, are metalliferous. But is Eaton correct in referring such limestone as that of which the New-York City-Hall is built, to a metalliferous class? Is not that limestone decidedly primitive? The fact mentioned of its containing pyrites, hardly proves it to be metalliferous; since most rocks contain more or less of pyrites. Some other remarks of less importance we might add, but we prefer concluding by recommending this tract to the perusal of those who wish for information respecting the geological structure of New-England; and we think that Mr. Eaton is seriously aiding the progress of geology in the interior of New-England. ART. XIII. _Notice of M. Brongniart on Organized Remains._ This distinguished mineralogist, so advantageously known by his excellent work on mineralogy--his researches in company with Cuvier, into the subterranean geography of the environs of Paris, and his superintendence of the great porcelain manufactory at Sevres, is attempting to form an extensive collection of organized remains. Through Professor Cleaveland, we have received from him the following NOTICE _Concerning the method of collecting, labelling, and transmitting specimens of fossil organized bodies, and of the accompanying rocks, solicited by_ M. BRONGNIART. The study of fossil organized bodies appears to be of the utmost importance in determining the relations of different formations, one of the principal objects of geology. In order more effectually to appreciate the value of this method of investigation, it is necessary to multiply observations--to endeavour to render them exact and precise--and especially to make them upon a general plan. M. Brongniart has been long occupied in such researches. The essay published by M. Cuvier and him, upon the geology of the environs of Paris, has afforded an example of their use. He has laboured since this period to apply this method to other formations, which contain the relics of organized bodies; but he stands in need of much assistance, and he presumes to ask it, not only of naturalists, but even of all persons interested in the sciences. By means of the following instructions, he endeavours to avail himself of the kindness of persons the least conversant in the discrimination of fossils.