After the completion of his great work Bloch prepared a general system of fishes, in which he arranged not only those previously described, but also those with which he had afterwards become acquainted. The work was ably edited and published after Bloch's death by a philologist, J. G. Schneider, under the title _M. E. Blochii Systema ichthyologiae iconibus cx. illustratum_ (Berl., 1801). The number of species enumerated amounts to 1519. The system is based upon the number of the fins, the various orders being termed _Hendecapterygii_, _Decapterygii_, &c. An artificial method like this led to the most unnatural combinations and distinctions. Bloch's _Naturgeschichte_ remained for many years the standard work. But as regards originality of thought Bloch was far surpassed by his contemporary, B. G. E. de Lacepède, born at Agen, in France, in 1756, who became professor at the museum of natural history in Paris, where he died in 1825. Lacepède. Lacepède had to contend with great difficulties in the preparations of his _Histoire des poissons_ (Paris, 1798-1803, 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 inaccessible to him for a long time. His work, therefore, abounds in the kind of errors into which a compiler is liable to fall. Thus the influence of Lacepède on the progress of ichthyology was vastly less than that of his fellow-labourer; and the labour laid on his successors in correcting numerous errors probably outweighed the assistance which they derived from his work. The work of the principal students of ichthyology in the period between Ray and Lacepède was chiefly systematizing and describing; but the internal organization of fishes also received attention from more than one great anatomist. Albrecht von Haller, Peter Camper and John Hunter examined the nervous system and the organs of sense; and Alexander Monro, _secundus_, published a classical work, _The Structure and Physiology of Fishes Explained and Compared with those of Man and other Animals_ (Edin., 1785). The electric organs of fishes (_Torpedo_ and _Gymnotus_) were examined by Réaumur, J. N. S. Allamand, E. Bancroft, John 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 _Salmonidae_ was known and practised by J. G. Gleditsch (1764). Bloch and Lacepède's works were almost immediately succeeded by the labours of Cuvier, but his early publications were tentative, preliminary and fragmentary, so that some little time elapsed before the spirit infused into ichthyology by this great anatomist could exercise its influence on all the workers in this field.