In his letter of presentation to the library of the Neuchatel Academy, addressed to M. le Baron de Chambrier, President of the Academic Council, Agassiz thus describes the Nomenclator. . . ."Have the kindness to accept for the library of the Academy the fifth number of a work upon the sources of zoological criticism, the publication of which I have just begun. It is a work of patience, demanding long and laborious researches. I had conceived the plan in the first years of my studies, and since then have never lost sight of it. I venture to believe it will be a barrier against the Babel of confusion which tends to overwhelm the domain of zoological synonymy. My book will be called 'Nomenclator Zoologicus.'". . . The Bibliographia (4 volumes, octavo) was in some measure a complement of the Nomenclator, and contained a list of all the authors named in the latter, with notices of their works. It appeared somewhat later, and was published by the Ray Society in England, in 1848, after Agassiz had left Europe for the United States. The material for this work also had been growing upon his hands for years. Feeling more and more the importance of such a register as a guide for students, he appealed to naturalists in all parts of Europe for information upon the scientific bibliography of their respective countries, and at last succeeded in cataloguing, with such completeness as was possible, all known works and all scattered memoirs on zoology and geology. Unable to publish this costly but unremunerative material, he was delighted to give it up to the Ray Society. The first three volumes were edited with corrections and additions by Mr. H.E. Strickland, who died before the appearance of the fourth volume, which was finally completed under the care of his father-in-law, Sir William Jardine.