The beginnings of a species, or of a subspecies, are obscure more often than not; and they are rarely to be declared with certainty. "Nothing is more difficult than to discover who have been in literature the first inventors" of a new form, so M. Jules Lemaitre once asserted, adding that innovations have generally been attempted by writers of no great value, and not infrequently by those who failed in those first efforts, unable to profit by their own originality. And it is natural enough that a good many sighting shots should be wasted on a new target before even an accomplished marksman could plump his bullet in the bull's-eye. The historical novel as we know it now must be credited to Scott, who preluded by the rather feeble 'Waverley,' before attaining the more boldly planned 'Rob Roy' and 'Guy Mannering.' The sea-tale is to be ascribed to Cooper, whose wavering faith in its successful accomplishment is reflected in the shifting of the successive episodes of the 'Pilot' from land to water and back again to land; and it was only when he came to write the 'Red Rover' that Cooper displayed full confidence in the form he had been the first to experiment with. But the history of the detective-story begins with the publication of the 'Murders in the Rue Morgue,' a masterpiece of its kind, which even its author was unable to surpass; and Poe, unlike most other originators, rang the bell the very first time he took aim. II The detective-story which Poe invented sharply differentiates itself from the earlier tales of mystery, and also from the later narratives in which actual detectives figure incidentally. Perhaps the first of these tales of mystery is Walpole's 'Castle of Otranto,' which appears to us now clumsy enough, with its puerile attempts to excite terror. The romances of Mrs. Radcliffe are scarcely more solidly built--indeed, the fatigue of the sophisticated reader of to-day when he undertakes the perusal of these old-fashioned and long-winded chronicles may be ascribed partly to the flimsiness of the foundation which is supposed to support the awe-inspiring super-structure. Godwin's 'Caleb Williams' is far more firmly put together; and its artful planning called for imagination as well as mere invention. In the 'Edgar Huntley' of Charles Brockden Brown the veil of doubt skilfully shrouds the unsuspected and the unsuspecting murderer who did the evil deed in his sleep--anticipating the somnambulist hero of Wilkie Collins's 'Moonstone.'