affinity in the writings of Müller, or even in the "Systema Naturæ;" as it is certain he yielded himself to the influence of Linnæus in retaining the Balani and Anatifæ in the class. Lamarck, already eminent amongst botanists, was at this time elected professor of zoology to the Museum of Natural History, and immediately began his efforts to reform the classification of the animals whose history it was his duty to expound. He is considered by his countrymen to have possessed the talent for method in a higher degree than any naturalist saving Linnæus; and there appears to be some justness in this appreciation of his character. His systematical essays are always based on accurate and extensive knowledge; and the foundations of his divisions are laid on characters of organization which must influence more or less the animal's economy. These divisions are, at the same time, uniformily defined with remarkable precision and neatness, so as to be well adapted to the purposes of the nomenclaturist. A happy example of this is found in his primary division of the animal kingdom into vertebrate and invertebrate animals,-terms so well chosen that they have become household words with us all, displacing from scientific nomenclature their Aristotelian equivalents, sanguineous and exsanguineous, which the progress of physiology had shown to be no longer applicable. In his first essay, of the date of 1799, Lamarck did not deviate from his predecessors in any thing essential. He divided the order Testacea into univalve, bivalve, and multivalve shells. The univalves were either unilocular or multilocular; the bivalves were irregular or regular; and the multivalves were as Linnæus left them. But in 1804 a new edition of his method bore very evident marks of Cuvier's influence upon its author. The method is as follows: NAKED. TESTACEOUS. MOLLUSCA. I. CEPHALOUS MOLLUSCA. Swimmers-Gen.: Sepia, Loligo, Octopus, Gasteropods-Gen.: Laplysia, Dolabella, ton. 1. Shell univalve unilocular ( Gen.: Patella, Fissurella, not spiral covering the Emarginula, Concholepas, animal Crepidula, Calyptræa. 2. Shell univalve unilocular spiral sheathing the animal. * Aperture emarginate, or channelled at its base. Gen.: Conus, Cypræa, Ovula, Terebellum, Oliva, Ancillaria, Voluta, Mitra, Columbella, Marginella, Cancellaria, Nassa, Purpura, Buccinum, Eburna, Terebra, Dolium, Harpa, Cassis, Strombus, Pterocera, Rostellaria, Murex, Fusus, Pyrula, Fasciolaria, Turbinella, Pleurotoma, Clavatula, Cerithium. ** Aperture entire and without a canal at its base. Gen.: Trochus, Solarium, Turbo, Monodonta, Cyclostoma, Scalaria, Pupa, Turritella, Ianthina, Bulla, Bulimus, Agathina, Limnæa, Melania, Pyramidella, Auricula, Valvata, Ampullaria, Planorbis, Helix, Helicina, Nerita, Natica, Testacella, Stomatia, Haliotis, Vermicularia, Siliquaria, Aspergillum, Carinaria, Argonauta. Gen. Nautilus, Orbulites, 3. Shell univalve multilocu- Ammonites, Planulites, NAKED. CONCHIFEROus. Nummulites, Spirula, Turrulites, Baculites, Orthocera, Hippurites, Belemnites. II. ACEPHALOUS MOLLUSCA. 1. Shell equivalve with or without accessary pieces. 2. Shell inequivalve of two) or more valves, of which the principal are unequal. Gen. Ascidia, Biphores, Gen. Pinna, Mytilus, Modiola, Anodonta, Unio, Nucula, Pectunculus, Arca, Cucullæa, Trigonia, Tridacna, Hippopus, Cardita, Isocardia, Cardium, Crassatella, Paphia, Lutraria, Mactra, Petricola, Donax, Meretrix, Venus, Venericardia, Cyclas, Lucina, Tellina, Capsa, Sanguinolaria, Solen, Glycimeris, Mya, Pholas. *Principal valve tubular. Gen. : Teredo, Fistulana. **Bivalve, the valves unequal. Gen.: Acardium, Radiolites, Cama, Spondylus, Plicatula, Gryphæa, Ostrea, Vulsella, Malleus, Avicula, Perna, Placuna, Pecten, Lima, Pedum, Pandora, Corbula, Anomia, Crania, Terebratula, Calceola, Hyalæa, Orbicula, Lingula. *** Multivalve and no hinge. Gen.: Anatifa, Balanus. This arrangement is inferior to the previous one of Cuvier in several respects; but the division of the Mollusca into two primary sections from the character of the head, is both convenient and physiologically correct, for it indicates corresponding modifications in the development of the nervous system. External habit likewise proves the value of the division. There is a wide difference in the physiognomy of a naked cephalous mollusk, and in that of a naked acephalous one, marking indisputably the superior faculties and structure of the former; and the shell of the testaceous mollusk that is headed is univalve or imbricate, while that of the acephala is uniformly bivalvular. But the chief merit of this artificial method is the creation of many new genera. Bruguiere had proposed sixty-one genera; Lamarck here raised the number to 126; and so well were they limited and true in nature, that they have been all retained in the most approved systems that followed. But Cuvier was the moving spirit that led to every useful reform. In a series of admirable essays published in the "Mémoires du Museum," he skilfully developed the anatomy of the principal genera of the Mollusca, and rendered his descriptive details interesting by the ease and perspicuity of his style, by his mastery of his subject and over all that had been done before him, and by his critical acumen in questionable points. His eloquent lectures told more immediately on his pupils, who arose around the great master in zealous numbers; and to two of them we are indebted for the publication of those lectures, which to this day declare the solidity of the fame they had so early procured him. In the volume published in 1800 there is the following synopsis of his method of classifying the Mollusca at that period: * Subsequently collected together, and published in a quarto volume, with the title "Mémoires pour servir à l'histoire et à l'anatomie des Mollusques, par M. le Chevalier Cuvier." Paris, 1817. It is essential to the library of the Conchologist. MOLLUSCA. I. THE HEAD ENCIRCLED WITH TENTACULA WHICH SERVE THE PURPOSES OF FEET. Fam. I. CEPHALOPODES. *Naked-Genus: Sepia. **Testaceous -Genera: II. THE HEAD DISTINCT, THE ANIMAL GASTEROPOD. Fam. ii. GASTEROPODES. *Shelless, or the Shell internal.-Genera: Doris, Phyllidia, Thetis, Limax, Testacella, Sigaretus, Aplysia. **Shelled. § Shell multivalve. Genus: Chiton. §§ Shell conical. Genus: Patella. §§§ Shell turbinate. (a) Aperture entire. Genera: Haliotis, Nerita, Turbo, Vermetus, Trochus, Bulla, Helix. (b) Aperture emarginate or effuse. Genera: Voluta, Ovula, Cypræa, Conus, Terebellum. (c) Aperture canaliculate. Genera: Murex, Strombus, Buccinum. III. No HEAD. Fam. iii. ACEPHALES. *The mantle membranous or coriaceous, and naked. The genera of Cuvier are the co-equals of the families of other naturalists. I do not quote his sub-genera, for they were confessedly borrowed from other authors. T It is difficult for us to perceive wherein Cuvier had benefitted from Lamarck in drawing up this arrangement, as Deshayes affirms, for its merits and improvements depend exclusively on the choice of characters for the main sections; and he had recourse to Lamarck only for the indication of the sub-genera. We need not tarry to point out the improvements here effected, for they will be obvious on a comparison with the previous synopsis; nor need I detain you with any notice of the crude and useless compilations of Bosc and of Denis Montfort-the latter the very Baron Munchausen of conchologists. M. de Roissy deserves, however, honourable mention, for his popular and well-executed continuation of the volumes of Buffon contributed to diffuse a knowledge and taste for our science. He neither invented a method nor created genera, but he was the first who attempted to complete Cuvier's system by intercalating, in their fit places, the genera of Lamarck. He annotated each of them with concise explanations; he occasionally set forth new views of their relations, and he added useful notices of the animal inhabitants,-all done with clearness and sagacity. Cuvier had just established a new order under the name of Pteropodes, embracing the genera Clio, Hyalæa, Pneumoderma, and the Firoles; and M. de Roissy hastened to adopt the order, placing it, at the suggestions of Cuvier, between the Cephalopods and Gasteropods. Henceforth the Hyalæa was withdrawn from the vicinage of the Terebratula and Anomia, where both Cuvier and Lamarck had misplaced it, before the former became acquainted with its anatomy. While Cuvier was thus pursuing his researches into the structure of the Mollusca, Lamarck's activity carried him in a different direction to study the fossils of the environs of Paris. His memoirs on these contain the descriptions of many new species, and are enriched with valuable observations on each genus. He discovered some new genera, amongst which we may specify the Clavagella, important as a link in connecting the Aspergillum with the acephalous mollusks that possess a calcareous tube. A zealous collector who had, with much perseverance, brought together the fossils of Grignon and other places, aided the work in placing his rich and beautiful collection at Lamarck's disposal. M. Defrance was the first, and then the only, naturalist who interested himself, in a scientific manner, with the fossils of the basin of Paris; and it is to his preliminary labours that the authors of the Geology of that basin are indebted for the well-determined lists of fossils on which their theory of its production is based. |