It may not be very generally known, excepting only among Naturalists, that the late Dr. Solander had devoted much attention to this intricate science: his arrangement of shells was designed as an amendment upon that of Linnæus. This arrangement was never made public; it remained in manuscript in the library of the late Sir Joseph Banks. From a perusal of these MSS. it appears that Dr. Solander had conceived the necessity of a new disposition of the shells comprised in general as varieties of this species. Some he allows to remain varieties, while others constitute, in his ideas, species nearly analogous, but nevertheless distinct. He does not propose the formation of an independant genus of the Harp family, nor the removal of those shells from the genus Buccinum, in which Linnæus places the species Harpa: he proposes only to assemble together the least equivocal varieties of that shell, together with that which he considers as the type of the Linnæan species, the true Harpa Nobilis of preceding authors; and to allow the others to remain as species distinct from the Linnæan shell. It will be hence perceived that Dr. Solander’s constitutes several distinct species among the number of those Harps, which other writers, and Gmelin among the rest, regard as varieties only of the common kind. In the manuscripts of Dr. Solander the very beautiful Harp shell now before us stands as a distinct species from Buccinum Harpa, under the name of _Buccinum testudo_. Some of the French Naturalists have called it _Harpa testudinaria_: it was placed under that name, and its synonymous appellation _L’ecaille de Tortue_ in the once celebrated Museum of Mons. de Colonne, the French Minister of State, under Louis the XVI: the definitive English name of Tortoiseshell Harp was assigned to it by Mr. George Humphrey, and from his known authority in the study of shells, this variety has been since distinguished among collectors in our country by that appropriate appellation. All these names, it will be scarcely necessary to add, are devised in allusion to that resemblance which its peculiarly beautiful variegations of colour are conceived to bear, to those of tortoiseshell, when transparent and exposed to light.