In his _Histoire des Progrès des Sciences naturelles_ Cuvier does it justice. Referring to the earlier volume, he states that "it has extended immensely the knowledge, especially by a new distribution, of the shelled molluscs ... M. de Lamarck has established with as much care as sagacity the genera of shells." Again he says, in noticing the three first volumes: "The great detail into which M. de Lamarck has entered, the new species he has described, renders his work very valuable to naturalists, and renders most desirable its prompt continuation, especially from the knowledge we have of means which this experienced professor possesses to carry to a high degree of perfection the enumeration which he will give us of the shells" (_Oeuvres complètes de Buffon_, 1828, t. 31, p. 354). "His excellences," says Cleland, speaking of Lamarck as a scientific observer, "were width of scope, fertility of ideas, and a preëminent faculty of precise description, arising not only from a singularly terse style, but from a clear insight into both the distinctive features and the resemblance of forms" (_Encyc. Britannica_, Art. LAMARCK). The work, moreover, is remarkable for being the first one to begin with the simplest and to end with the most highly developed forms. Lamarck's special line of study was the Mollusca. How his work is still regarded by malacologists is shown by the following letter from our leading student of molluscs, Dr. W. H. Dall: "SMITHSONIAN INSTITUTION, "UNITED STATES NATIONAL MUSEUM, WASHINGTON, D. C., "_November 4, 1899._ "Lamarck was one of the best naturalists of his time, when geniuses abounded. His work was the first well-marked step toward a natural system as opposed to the formalities of Linné. He owed something to Cuvier, yet he knew how to utilize the work in anatomy offered by Cuvier in making a natural classification. His failing eyesight, which obliged him latterly to trust to the eyes of others; his poverty and trials of various kinds, more than excuse the occasional slips which we find in some of the later volumes of the _Animaux sans Vertèbres_. These are rather of the character of typographical errors than faults of scheme or principle. "The work of Lamarck is really the foundation of rational natural malacological classification; practically all that came before his time was artificial in comparison. Work that came later was in the line of expansion and elaboration of Lamarck's, without any change of principle. Only with the application of embryology and microscopical work of the most modern type has there come any essential change of method, and this is rather a new method of getting at the facts than any fundamental change in the way of using them when found. I shall await your work on Lamarck's biography with great interest. "I remain, "Yours sincerely, "WILLIAM H. DALL." FOOTNOTES: