The extent of the genus has been most vaguely estimated; by some enumerated at two hundred and forty; an estimate that must certainly include many very slight varieties, which, if allowed, might swell the genus to ten times its real extent. But we think a rational computation would confine them within a hundred, including every distinct variety. The author’s intention is to figure only those to which a separate character can be affixed, regarding a superfluous repetition, even of beauty, inadmissible. As the merits of the present undertaking may easily be appreciated by a free access to all its beautiful originals, the author hopes a candid allowance will be made, upon a comparison with the living plant, when it is considered that the most elaborate efforts of art have never yet been able to do justice to its superior beauty.