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 entered into detailed researches of the organs of respiration.
A new era in the history of Ichthyology commences with Ray, Willughby, and Artedi, who were the first to recognise the true principles by which the natural affinities of animals should be determined. Their labours stand in so intimate a connection with each other that they represent only one stride in the progress of this science.
Ray and Willughby. J. Ray (born 1628 in Essex, died 1705), was the friend and guide of F. Willughby (1635-72). They had recognised that a thorough reform of the treatment of the vegetable and animal kingdoms had become necessary; that the only way of bringing order into the existing chaos was that of arranging the various forms with regard to their structure; that they must cease to be burdened with inapplicable passages and quotations of the ancient writers, and to perpetuate the erroneous or vague notions of their predecessors. They abandoned speculation, and adhered to facts only. One of the first results, and perhaps the most important, of their method was, that having recognised the "species" as such, they defined this term, and fixed it as the base, from which all sound zoological knowledge has to start.
Although they had divided their work thus that Ray attended to the plants principally, and Willughby to the animals, the "Historia piscium" (Oxford, 1686, fol.), which bears Willughby's name on the titlepage, and was edited by Ray, is clearly their joint production. A great part of the observations contained in it were collected during their common journeys in Great Britain and on the Continent, and it is no exaggeration to say that at that time these two English-
