Lacépède had to contend with great difficulties in the preparation of his “Histoire des Poissons” (Paris, 1798–1803, 4to, in 5 vols.), which was written during the most disturbed period of the French Revolution. A great part of it was composed whilst the author was separated from collections and books, and had to rely on his notes and manuscripts only. Even the works of Bloch and other contemporaneous authors remained unknown, or at least inaccessible, to him for a long time. Therefore we cannot be surprised that his work abounds in all those errors to which a compiler is subject. The same species not only appears under two and more distinct specific names, but it sometimes happens that the author understands so little the source from which he derives his information that the description is referred to one genus and the accompanying figure to another. The names of genera are unduly multiplied; and the figures with which the work is illustrated are far inferior to those of Bloch. Thus the influence of Lacépède on the progress of Ichthyology was infinitely less than that of his fellow-labourer; and the labour caused to his successors by correcting the numerous errors into which he has fallen, probably outweighs the assistance which they derived from his work. [Sidenote: Anatomists.] The work of the principal cultivators of Ichthyology in the period between Ray and Lacépède was chiefly systematic and descriptive, but also the internal organisation of fishes received attention from more than one great anatomist. _Haller_, _Camper_, and _Hunter_, examined the nervous system and organs of sense; and more especially _Alexander Monro_ (the son) published a classical work, “The Structure and Physiology of Fishes explained and compared with those of Man and other Animals” (Edinb. 1785, fol.) The electric organs of fishes (_Torpedo_ and _Gymnotus_) were examined by _Réaumur_, _Allamand_, _Bancroft_, _Walsh_, and still more exactly by _J. Hunter_. The mystery of the propagation of the Eel called forth a large number of essays, and even the artificial propagation of Salmonidæ was known and practised by _Gleditsch_ (1764). [Sidenote: Faunists.]