Works on natural history have divers objects in view, and may be intended either for popular and general distribution, or for special scientific purposes, and in each case the mode of treatment will materially differ. Many purposes may also be intended to be severally met in the strictly and rigidly scientific treatment. They may be either general methodical arrangements treated superficially, having no other design than to give a sort of bird’s-eye view of the subject in its wider distributions and broader landmarks, or they may treat of portions of the large subject more specially; again, they may constitute monographs of varying extent from a family to a genus; or they may comprise loose descriptions of new species of old and well-established genera; and some such, conjunctively with new species, establish likewise new genera, indicating, at the same time, their proximate position in the general series. The two latter classes are usually the appendages to voyages and travels in distant unexplored countries, or are the result of a careful collection of neglected tribes at home. Each, thus, with its special application has its special construction; but in the case of new species, I would strenuously counsel a full and complete description, and urge as imperative the construction of a specific character, formally framed to meet the condition of the science, based upon the precise antecedents and existing state of the genus to which such species belong. Even assuming that the knowledge of species is the essential foundation of the science, the preceding observations show that there is a higher knowledge connected with the pursuit than this mere knowledge of species, and yet from which it emanates. There is a higher object to be achieved than the accumulation of a store of them, arranged in seemly order, set with manifest taste, and named in accordance with the accepted nomenclature. These are extremely pleasing to the eye, but the intellect languishes over them in unsatisfied desire, craving more solid aliment. There is besides room for observation on every side, either confirmatory or original, and both are much needed, and must be considerably augmented before it is accumulated in satisfactory abundance; and until this be procured, existing systems can be viewed merely as temporarily useful, for until all that nature can teach shall be exhausted, perfection cannot be attained.