The above series of Davila presents us with a pretty ample elucidation of the presumed varieties of that beautiful species the Linnæan Buccinum Harpa. We say, only the presumed varieties, because in the present state of the Conchological Science there appears to be a very strong propensity among collectors to increase the number of the species, by considering every trivial variation, or accidental circumstance in the growth of shells, as so many characteristic indications of new species; a disposition that the best Conchologists cannot but disapprove. Experience teaches us that there is no class of beings in the creation, in which nature is more sportive, than the testaceous tribes; none in which a greater caution is required in the precise determination of what are species and what varieties only: and among other local causes the influence of climates in different regions are not the least powerful in producing those variations. With the best experience, and the advantage of many years assiduous application, the Conchologist may be sometimes in doubt, and hence it is not likely that a slight acquaintance, only, with the subject will be found sufficient to enable him to pronounce with definitive satisfaction the exact distinction between approximating species and the sportive varieties into which they sometimes divaricate. These remarks cannot be more forcibly exemplified than in the series of the presumed varieties of the Buccinum Harpa. Some of these are indeed so very dissimilar as to justify a persuasion that they may be specifically distinct, and yet again, these are blended so intimately with others, which are confessedly varieties, that it demands the utmost caution in pronouncing which are species, and which varieties or transitions only. This is the impression under which the best informed Conchologists have ever ventured to define the shells which constitute the natural family of the Harps, and may serve to afford us a sufficient explanation of the causes of those differences in opinion which so manifestly prevail among them.