The Work will be issued in forty-five numbers viz., forty-four of Plates and one of Text, each number of Plates containing ten—printed on seven sheets double-elephant paper, of the best quality for the purpose, 27 by 40 inches, and will be delivered to Subscribers Monthly, at £2, 8s. per number; the last Number, comprising seven volumes of Text, to be delivered bound with the fifteenth number. It is intended that each Number shall contain as follows: Viz. two large Plates, each occupying the whole sheet; two of a medium size, each occupying also the entire sheet; and six of the smaller size, two Plates on a sheet; thus presenting ten of the original Plates on seven sheets, giving a variety in each number. The text is properly and scientifically classified, and when the Work shall be completed the Plates can be placed and be bound corresponding with the order of the Text, in either three or four Volumes. The regular issue of the Numbers will commence so soon as the number of Subscribers will justify the undertaking. As the Work will be published for Subscribers alone, few or none being printed beyond the number subscribed for, it is not possible that its pecuniary value can ever be much reduced; on the other hand, the probabilities are that it will rather be increased. Nor will there ever be a time when it can be published at a less price than the present; for in estimating the cost the mere expense of manufacturing has been taken into consideration, without reference to the original cost of the Copper-plates, which was nearly One hundred thousand Dollars; and a very small profit has been charged on the expense thus estimated. The first Number is considered superior in many respects to the same Plates in the first Edition, and it is confidently hoped that subsequent Numbers will exhibit still greater superiority as the Artists gain experience. A full list of Subscribers will be published with the Work. The Numbers will not be sold separately, except the first, which will be sent, properly packed, as a Specimen, to any part of the country, free of expense, on the receipt of £2, 8s. Orders or communications to Trübner & Co., Booksellers, 60, Paternoster Row, London. New York, March 31, 1859. J. W. AUDUBON. * * * * * Trübner & Co. also offer to the Trade and the Public the following Editions of Audubon's Birds and Quadrupeds of North America: Birds of North America—Library Edition, 7 vols., royal 8vo., with 500 finely colored Plates, from Drawings made in the United States and their Territories. Price £25. Quadrupeds of North America,—By J. J. Audubon and Rev. John Bachman. Original Edition, 3 vols. imperial folio, bound in half russia. One hundred and fifty superbly colored Plates. With descriptive letter-press, in 3 vols., royal 8vo. Price £63. The same work,—Library Edition, 3 vols. royal 8vo. with one hundred and fifty-five finely colored Plates. Price £9, 9s.