LEACH, WILLIAM ELFORD, was born at Plymouth in the year 1790. He was first educated at Plympton Grammar School, but was afterwards removed to Chudleigh, a school which at that period enjoyed much local repute. Though not noticed as idle, his inclination was shown at this early period more in the pursuit of external objects than in the attentive study of his school books. Both at Plympton, and afterwards at Chudleigh, he was in the constant habit of storing up material of supposed interest, and forming collections of natural objects, in -which he never failed to secure the co-operation of his schoolmates. These juvenile collections fixed the study of natural science early in his mind, and induced him to choose the profession of medicine as facilitating him in its progress. In pursuance of this idea he was apprenticed to the Devon and Exeter Hospital in the year 1807. Here ho distinguished himself among his fellow pupils for the skill with which he performed the minor operations in surgery, as also for the general gaiety of his disposition and the energy and determination of purpose he evinced in whatever he undertook.
In 1808 he went to London, where he entered at St. Bartholomew's Hospital, Abernethy at the time being at the head of its medical school. In 1809, after only a single year's study, he obtained the diploma of the Royal College of Surgeons. He then proceeded to Edinburgh to complete his studies. While there he laid before the Wernerian Society one or two papers on comparative anatomy and zoology, and such was his zeal and reputation as a successful student that the degree of ILD. was conferred upon him at the comple tion of his second year, a very remarkable honour, and one rarely granted. But Dr. Leach is known not as a physician but as a naturalist, and as such we must contemplate his history; and in the whole field of science no more zealous or industrious student ever laboured. He was deterred by no difficulty, yielding to neither fatigue of mlad or body. From Edinburgh he proceeded to London to tako charge of the natural history department of the British Museum ; and here to appreciate Dr. Leach's labours it would be necessary to review the state of the natural sciences, and zoology in particular, at the commencement of the present century, at a length which cannot be brought within the space allotted to this notice.
The artificial system of classifying objects invented by Linnaeus was at this time prevalent thrdughout Europe, but the defects were becoming increasingly perceptible in every ;part of natural history, but mostly so in the lower forms of zoology. It was in France that the first opposition to the artificial system was commenced by Daubenton and Pallas, whose immature labours were speedily followed by those of Lamarck and Cuvier. But while zoology was making rapid strides on the Continent there were few in England who followed up the path thus opened to them, there being a general repug nance to anything that appeared like an innovation on this system. Leach was among the first who appreciated the natural arrangement which had so long guided tho continental zoologists ; and for the introduction of which into this country we are mainly indebted to him. He not only pursued the path which others had opened, but he advanced the subject by his individual researches, and produced the first movement towards weaning his countrymen from the school to which they had too long adhered.
Ho pursued his labours at the British Museum with a zeal scarcely to he surpassed, and won the esteem and confidence of all with whom he was brought into contact. One of the first results after his appointment was the publication of the 'Zoologist's Miscellany,' a continuation of tho irregular serial commenced by Mr. Shaw his predecessor, under the name of the 'Naturalist's Miscellany.' This work Leach continued until 1817, and completed three volumes. Although his duties required his attention to be given to the whole of the animal kingdom, yet at this time in particular he laboured chiefly at the Articulate, the results of his residence upon the coast of Devonshire directing his attention more particularly to the Crustacea, to which class of aoimals ho added many new discoveries. In 1813 he published an article Crustaceology,' the arrangement of which he revised and corrected in a paper in the Transactions of the Linnsean Society,' the chief feature in which was the separation of the Myriopoda, Arsehnides, and Insects from the Crustacea, the whole of which previously had been arranged by Linnnus under Irtsecla, while Latreille and Lamarck had grouped the Myriopoda with the Arachnides.