SEYCHELLES.—The rocky islands of primary formation, composing this group, rise from a very extensive and tolerably level bank, having a depth between twenty and forty fathoms. In Captain Owen’s chart, and in that in the “Atlas of the Voyage of the _Favourite_,” it appears that the east side of _Mahe_ and the adjoining islands of _St. Anne_ and _ Cerf_, are regularly fringed by coral-reefs. A portion of the S.E. part of _Curieuse Island_, the N., and part of the S.W. shore of _Praslin Island_, and the whole west side of _Digue Island_, appear fringed. From a MS. account of these islands by Captain F. Moresby, in the Admiralty, it appears that _ Silhouette_ is also fringed; he states that all these islands are formed of granite and quartz, that they rise abruptly from the sea, and that “coral-reefs have grown round them, and project for some distance.” Dr. Allan, of Forres, who visited these islands, informs me that there is no deep water between the reefs and the shore. The above specified points have been coloured red. _ Amirantes Islands_: The small islands of this neighbouring group, according to the MS. account of them by Captain F. Moresby, are situated on an extensive bank; they consist of the debris of corals and shells; are only about twenty feet in height, and are environed by reefs, some attached to the shore, and some rather distant from it.—I have taken great pains to procure plans and information regarding the several islands lying between S.E. and S.W. of the Amirantes, and the Seychelles; relying chiefly on Captain F. Moresby and Dr. Allan, it appears that the greater number, namely—_Platte, Alphonse, Coetivi, Galega, Providence, St. Pierre, Astova, Assomption_, and _ Glorioso_, are low, formed of sand or coral-rock, and irregularly shaped; they are situated on very extensive banks, and are connected with great coral-reefs. Galega is said by Dr. Allan, to be rather higher than the other islands; and St. Pierre is described by Captain F. Moresby, as being cavernous throughout, and as not consisting of either limestone or granite. These islands, as well as the Amirantes, certainly are not atoll-formed, and they differ as a group from every other group with which I am acquainted; I have not coloured them; but probably the reefs belong to the fringing class. Their formation is attributed, both by Dr. Allan and Captain F. Moresby, to the action of the currents, here exceedingly violent, on banks, which no doubt have had an independent geological origin. They resemble in many respects some islands and banks in the West Indies, which owe their origin to a similar agency, in conjunction with an elevation of the entire area. In close vicinity to the several islands, there are three others of an apparently different nature: first, _Juan de Nova_, which appears from some plans and accounts to be an atoll; but from others does not appear to be so; not coloured. Secondly _Cosmoledo_; “this group consists of a ring of coral, ten leagues in