I have the pleasure to announce to the botanists, that the genus _Myosurus_, hitherto thought an European genus, and composed of a single species, has been detected in the United States by Dr. Short of Kentucky, who has discovered it in the neighbourhood of Hopkinsville, in Christian county, West Kentucky, and has communicated me specimens of it; by which, on comparing them with the European _Myosurus_, figured in _Flora Danica_, Lamarck's Illustrations, &c. I have been enabled to ascertain, that the American plant must form a second species of that genus, which I have accordingly dedicated it to the discoverer, by naming it _Myosurus Shortii_. This adds another genus and another new species to our Flora. I add the comparative definitions of the two species, exhibiting; their different characters and diagnosis. _Myosurus minimus._ Lin. &c. Leaves linear-cuneate, broader near the top, and acute. Scapes as long as the leaves, thickened towards the upper part. Calix 5 leaved, Spurs consimilar: petals 5. Stamens 5 to 8. Carpophore as long as the scapes. _Myosurus Shortii._ Raf. Leaves linear obtuse, hardly attenuated below. Scapes shorter than the leaves, and filiform. Calix 3 to 5 leaved, spurs membraneous: petals 3 to 5. Stamens 10 to 12. Carpophore shorter than the scapes. C. S. RAFINESQUE. _Philadelphia, May 1, 1819._ ART. XI. _Description of a New Species of Gnaphalium, by Professor_ E. IVES. _To B. Silliman, Esq. M.D., &c._ The following description of a new species of Gnaphalium, accompanied with a drawing, has been in my possession for two years. If the subsequent observations will be of use to correct error, or solve doubts which may have existed concerning some species of gnaphalium, they are at your service. E. IVES. This plant was first observed by me, in company with Mr. C. Whitlow, in July, 1817, by the margin of a brook, a few rods north of Mr. E. Whitney's gun manufactory, near New-Haven. It is also found on the margin of the Housatonick, about thirty miles from Long Island sound, where it was observed by Dr. Alfred Monson, the last summer. Specimens of this plant were sent to Z. Collins, Esq. of Philadelphia, for the purpose of comparing it with the species of gnaphalium in Muhlenberg's herbarium, more particularly with the _luteo-album_ and _Pennsylvanicum_, which I had not seen. [Illustration: _Gnaphalium decurrens._] I am indebted to the politeness of Mr. Collins, for the facts on this subject relative to Muhlenberg's herbarium. He observes, "your Gnaphalium is certainly not the _luteo-album_ of Muhlenberg, which may not strictly be a native, but introduced. Yours most approaches G. polycephalum Mx. Still, from the decurrent leaves and other differential marks, it appears to me to be a new species. Muhlenberg's collection has it not."