On this singular class of strata, reposes an extensive calcareous formation, occupying the northern and eastern part of the island, having _subordinate_ to it, and at its lowest part, where it is in contact with the conglomerate, large beds and patches of chert, which contains also a vast variety of petrified woods, several of which are of the palm tribe, with silicified shells, chiefly _cerithea_; though at the Church-hill, at St. Johns, formed of this chert, casts of bivalve and ramose madrepores are likewise found. The calcareous beds are principally of a friable marl, with blocks and layers of limestone irregularly included. In this _formation_[20] are many fossil shells, both in the calcareous and siliceous state; and there appear to be some beds, wherein is a mixture of shells of marine, and others of a fresh water, or at least a terrestrial origin. The coralline agates found in nodules and patches therein, and which may readily be distinguished from the coralline chert of the previous beds, are the most beautiful which have any where been yet noticed; and when well selected and polished, make very pleasing ornaments. The island, as well as Barbuda, thirty miles to the northward, the Grande Terre part of Guadaloupe, at a similar distance to the southward and eastward, with several others of the West-India Islands, give proof of an extensive formation, more recent than those to which naturalists have heretofore principally confined their' attention; and which is, perhaps, contemporaneous with, if not later than, the Paris Basin, so well described by Cuvier and Brongniart. _April 10th, 1818._ N. N. N. B. A few specimens are sent. REMARKS. If the above paper be read attentively, in connexion with that in No. 1. on the petrified wood of Antigua, it will afford some very curious information to the geologist respecting these petrifactions, and must lead to interesting speculations respecting their origin, under circumstances so very peculiar, and to which we do not recollect to have heard of any parallel. ART. IX. _Discovery of Native Crystallized Carbonate of Magnesia on Staten-Island, with a Notice of the Geology and Mineralogy of that Island, by_ JAMES PIERCE, ESQ. _of New-York, in a Letter to the Editor_. NEW-YORK, October 19, 1818. DEAR SIR,