TESTACEOUS FISH. 



353 





are found, they are universally known to be 

 composed of one arid the same substance. 

 They are formed of an animal or calcareous 

 earth, that ferments with vinegar and other 



The first to raise us from this enchained slumber was 

 Cuvier. Before this great naturalist entered the field, 

 Poli, a Neapolitan physician, had indeed anatomized 

 with admirable skill the bivalved mollusca of his native 

 shores, and had constructed a new arrangement of them 

 from the characters of the animal alone, but partly from 

 the political position of Europe, partly from the very ex- 

 pensive fashion in which Poli's work was published, and 

 its consequent extremely limited circulation, and in part 

 also from the partial application of his system and its did- 

 actic character, the erroneousness of his general views, 

 and the novelty of his nomenclature, we cannot trace 

 Its influence either as diffusive or propulsive of con- 

 chology. The result of Cuvier's labours was happily 

 very different. In 1788, when he was scarcely nine- 

 teen years of age, circumstances fixed Cuvier for a time 

 at Caen in Normandy. His sojourn on the borders of 

 the sea induced him, already an enthusiast in natural 

 history, to study marine animals, more especially the 

 mollusca, and the anatomies of them which he now 

 made conducted him to the developemeut of his great 

 views on the whole of the animal kingdom. With un- 

 wearied zeal he collected the materials which were at no 

 distant date to become the basis of a classification which 

 ran through all its details in a harmonious parallelism 

 with the developement of organization, so that the stu- 

 dent of it, when in search of the name and place of the 

 object in his hand, was necessitated simultaneously to 

 acquire a knowledge of its principal structural peculi- 

 arities, on which, again, as Cuvier beautifully explained, 

 all its habits in relation to food, to habitation, and to 

 locomotion, were made dependant. The Liausean sys- 

 tem of avertebrated animals, even in its primary sections, 

 rested on a single external character. The Insecta were 

 antennulated, and the Vermes were tentaculated averte- 

 hrates. Had the character been constant or even general, 

 it might have had some claim for adoption, but to a want 

 of constancy was added the fundamental defect of its in- 

 appreciable influence over the organisms of the body. 

 Cuvier's object being to give us not merely a key to the 

 name, but to make that key open at the same time a 

 knowledge of the structure and relations of the creature, 

 such arbitrary assumption of a character was to him 

 useless. After innumerable dissections had made him 

 familiar with many structures, and after a careful con- 

 sideration of the respective value of characters, as 

 shown iu their constancy and influence on the economy 

 of the species, Cuvier resolved to divide the animal 

 kingdom, not as hitherto into two, but into four prin- 

 cipal sub-kingdoms, drawing their Hues of separation 

 from differences exhibited in the plan on which their 

 muscular, their nervous, and their circulating systems 

 were formed. " There exist in nature," he says, "four 

 principal forms, or general plans, according to which all 

 animals seem to have been modelled, and the ulterior 

 divisions of which, whatever name the naturalists may 

 apply to them, are but comparatively slight modifica- 

 tions, founded on developement or addition of certain 

 parts, which do not change the essence of the plan." 

 Of these forms the mollusca furnish the second, of which 

 the essential character is derived from the peculiar ar- 

 rangement of the nervous system, consisting of some 

 ganglions scattered as it were irregularly through the 

 body, and from each of which nerves radiate to its vari- 

 ous organs. As there is no skeleton, so the muscles are 

 attached to the skin, which forms a soft contractile en- 

 velope protected, in many species, by a shell. The 

 greater number possess the senses of taste and sight, but 

 the last is often wanting. " Only one family can boast 

 VOL. n. 



acids, and that burns into lime, and will not 

 easily melt into glass. Such is the substance 

 of which they are composed ; and of their 

 spoils, many philosophers think that a great 



of the organ of hearing ; they have always a complete 

 system of circulation, and organs peculiarly adapted to 

 respiration ; those ot digestion and secretion are nearly 

 as complicated as the same organs in vertebrated ani- 

 mals." The sub-kingdom, characterized and limited 

 by those important features, is next divided into six 

 classes, the characters of which are mostly derived from 

 the organs of locomotion, or others not less influential. 

 Thus the Cephalopodes bear their feet and arms like a 

 coronet round the summit of the head ; the Pteropodes 

 swim in their native seas by fin-like oars ; and the 

 Gasteropodes crawl on the belly by means of a fiat disk 

 or sole. Reaching now tribes among whom the organs 

 of motion are less developed, and accordingly less 

 influential on their manners, Cuvier resorts to others. 

 Thus the fourth class is named Acephales, because it is 

 strikingly distinguished by the want of head and amorph- 

 ous form of its constituents; the Brachiopodes are 

 equally acephalous, but near the mouth they have two 

 fringed fleshy organs which simulate feet ; and the 

 Cirropodes have several pairs of subarticulated fringed 

 feet, in addition to a multivalved shell of a peculiar con- 

 struction. The orders of these classes, when the class 

 admits of further subdivision, rest upon distinct differ- 

 ences in the structure and position of the branchiae or 

 respiratory organs ; and when we reflect a moment on 

 the paramount necessity of these to the animal, and their 

 necessary co-adaptation to its locality and wants, it is 

 scarcely possible to conceive that a happier choice could 

 have been made.* 



Early in 1799, Lamarck published his Prodromus of 

 a new classification of shells, laying down, more precise- 

 ly, the generic characters, and establishing many new 

 genera, and still continuing the old division into uni- 

 valves, bivalves, and multivalves. Up to this time, La- 

 marck does not seem to have profited much by the la- 

 bours of his predecessors towards the establishment of a 

 natural conchyliological method, but acknowledges that 

 he has adopted the principles and views of Bruguiere. 

 Late in 1799, Cuvier published a table of the divisions 

 of the class of mollusca, at the end of the first volume of 

 his Lessons of Comparative Anatomy. We see, in this, 

 that Cuvier derived light from the Prodromus of La- 

 marck. Indeed, these two great naturalists, by their 

 successive works, seem to have allbrded light alternately 

 to each other for a number of years. In 1801, Lamarck 

 published his Animaux sans Vertdbres, in which, not 

 confining himself entirely to the shells, he has, like Cu- 

 vier, paid atttention also to the animals. From this pe- 

 riod until 1822, when he finished publishing the second 

 edition of Animaux sans FertHbres, under the title of 

 Histoire nuturelle des Animaux suvs Fertdbres, many 

 authors, both continental and British, had published me- 

 moirs and treatises on conchology, and many interesting 

 facts had been collected, shedding much additional light 

 on the science. Part of the 5th and the whole of the 

 6th and 7th volumes of the Histoire naturelle des Ani- 

 maux sans VertGbres, are devoted to the conchyliopho- 

 rous animals, the proper subjects of conchology. In this 

 excellent work, Lamarck has improved upon the views 

 of his friend Bruguiere in the following particulars : 

 not confining himself to the consideration of the shell ; 

 viewing the shell as forming part of an animal; introdu- 

 cing into conchology a great number of new generic 

 groups ; using a very rigorous and exact terminology ; 



* For the above sketch of the different systems of cnnchologv, 

 we are indebted to an elaborate article on the History of Con. 

 chology, in the Magazine of Zoology and Botany, Edinburgh. 



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