HISTORY.] ICHTHYOLOGY 631 13 n. P. BeloQ travelled in the countries bordering on the eastern part of the Mediterranean, in the years 1547-50; he collected rich stores of positive knowledge, which he embodied in several works. The one most important for the progress of ichthyology is that entitled De aquatilibus libri duo, Paris, 1553. Belon knows about one hundred and ten fishes, of which he gives rude but generally recog nizable figures. In his descriptions he pays regard to the classical as well as to the vernacular nomenclature, and states the outward characteristics, sometimes even to the number of fin rays ; frequently also he gives the most conspicuous anatomical peculiarities. Although Belon but rarely gives definitions of the terms used by him, it is not generally very difficult to ascertain the limits which he intended to assign to each division of aquatic animals. He very properly divides them into such as are provided with blood and those without it, two divisions corresponding in inoJern language to vertebrate and invertebrate aquatic animals. The former are classified by him according to size, the further subdivisions being based on the structure of the skeleton, mode of propagation, number of limbs, form of the body, and physical character of the habitat. ir iani. The work of the Horn an ichthyologist, H. Salviani (1514-72), bears evidence of the high social position which the author held as physician to three popes. Its title is Aquatilium animalium hintona, Rome, 1554-57, fol. It treats exclusively of the fishes of Italy. Ninety- two species are figured 011 seventy-six plates, which, as re gards artistic execution, are masterpieces of that period, although those specific characteristics which nowadays constitute the value of a zoological drawing were entirely overlooked by the author or artist. No attempt is made at a natural classification, but the allied forms are generally placed in close proximity. The descriptions are quite equal to those given by Belon, entering much into the details of the economy and uses of the several species, and were evidently composed with the view of collecting in a read able form all that might prove of interest to the class of society in which the author moved. Salviani s work is of a high order, very .remarkable considering the age in which he lived. It could not fail to convey valuable instruction, and to render ichthyology popular in the country to the fauna of which it was devoted, but it was not fitted to advance ichthyology as a science generally; in this respect Salviani is not to be compared with Ilondelet or Belon. 1 klet. G. Ilondelet (1507-57) had the great advantage over Belon of having received a medical education at Paris, and especially of having gone through a complete course of instruction in anatomy as a pupil of Guentherus of Andernach. This is conspicuous throughout his works Libri Je pisdbtis marinis, Lyons, 1554; and Universes aquatilium hiaturice pars altera, Lyons, 1555. Neverthe less they cannot be regarded as more than considerably enlarged editions of Belon s work. For, although he worked independently of the latter, and differs from him in nume rous details, of which he had a much more extensive know ledge, the system adopted by him is characterized by the same absence of the true principles of classification. His work is almost entirely limited to European and chiefly to Mediterranean forms, and comprises no less than one hundred and ninety-seven marine and forty- seven fresh water fishes. His descriptions are more complete and his figures much more accurate than those of Belon ; and the specific account is preceded by introductory chapters, in j which he treats in a general manner of the distinctions, the ! external and internal parts, and the economy of fishes. Like Belon, he had no conception of the various categories of classification confounding, for instance, throughout his work the terms " genus " and " species "; but he had an intuitive notion of what his successors called a " species," , and his principal object was to collect and give as much information as possible regarding such species. For nearly a century the works of Belon and Piondelet continued to be the standard works on ichthyology; but the science did not remain stationary during that period. The attention of naturalists was now directed to the fauna of foreign countries, especially of the Spanish and Dutch possessions in the New World ; and in Europe the estab lishment of anatomical schools and academies led to careful investigation of the internal anatomy of the most remark able European forms. Limited as these efforts were as to their scope, being restricted either to the fauna of some par ticular district or to the dissection of a single species, they were sufficiently numerous to enlarge the views of naturalists, and to destroy that fatal dependence on preceding autho rities which had continued to keep in bonds the minds of such men even as Rondelet and Belon. The most note worthy of those engaged in these inquiries in tropical countries were W. Piso and G. Margrav, who accompanied as physicians the Dutch governor, Prince Maurice of Nassau, to Brazil (1637-44). Of the men who left records of their anatomical re searches, we may mention Borelli (1C08-79), who wrote a work De motu animalium, Home, 1G80, 4to, in which he explained the mechanism of swimming and the function of the air-bladder; M. Malpighi (1628-94), who examined the optic nerve of the sword-fish ; the celebrated J. Swammerdam (1637-80), who described the intestines of numerous fishes; and J. Duverney (1648-1730), who investigated in detail the organs of respiration. A new era in the history of ichthyology commences with Ray, Willughby, and Artedi, who were the first to recog nize the true principles by which the natural affinities of animals should be determined. Their labours stand in so intimate a connexion with each other that they represent but one great step in the progress of this science. J. Ray (1628-1705) was the friend and guide of F. Ray and Willughby (1635-72). They found that a thorough Willugh- reform in the method of treating the vegetable and animal 3y kingdoms had become necessary; that the only way of bringing order into the existing chaos was by arranging the various forms according to their structure; that they must cease to be burdened with inapplicable passages and quo tations from ancient writers, and to perpetuate the vague and erroneous notions of their predecessors. They therefore substituted facts for speculation, and one of the first re sults of this change, perhaps the most important, was that, having recognized " species" as such, they defined the term, and fixed it as the starting point of all sound zoological knowledge. Although they had divided their work so that Ray attended to the plants principally, and Willughby to the animals, the Ilistoria pisciitm, Oxf., 1686, which bears Willughby s name on the title page, and was edited by Ray, is clearly their joint production. A great part of the observations contained in it were collected during the | journeys they made together in Great Britain and in the 1 various countries of Europe ; and it is no exaggeration to say that at that time these two Englishmen knew the fishes of the Continent, and especially those of Germany, better than any native zoologist. By the definition of fishes as animals with blood, breathing by gills, provided with a single ventricle of the heart, and either covered with scales or naked, the Cetaceans are excluded. The fishes proper are arranged primarily according to the cartilaginous or the osseous nature of the skeleton, and then subdivided according to the general form of the body, the presence or the absence of ventral fins, the soft or the spinous structure of the dorsal rays,
the number of dorsal fins, &c. No fewer than four
