74 T>r Geo. Johnston's Rmnarkff on the class Mollusca^ 



quelque branche de Tindustrie humaine, il donne au peuple qui 

 s''en empare le premier, ou qui Fexploite sur la plus grande 

 echelle, un puissant moyen de superiorite sur les autres peuples. 

 Souvent, enfin, ie renversement des rapports de prosperite, de 

 richesse, et de puissance entre les nations, est la suite necessaire 

 de I'adoption et du progres des applications d'une espece nouvelle 

 de forces mecaniques."" — Dupin. 



A Jew Remarks on the class MoUusca^ in Dr Fleming's Work 

 on British Animals; with Descriptions of some new Species. 

 By George Johnston, M. D. Fellow of the Royal College 

 of Surgeons of Edinburgh. — (Communicated by the Author.) 



V^UR progress in the study of invertebrate animals, has here- 

 tofore been much retarded by the labour of consulting many un- 

 connected volumes, through which our knowledge lay scattered ; 

 and still more by the imperfections of the system which their au- 

 thors had adopted. Beings of the most dissimilar structure, and 

 of the most opposite habits, were associated under one common 

 name ; and the learner went on, puzzled and perplexed, until 

 repeated failures had taught him, that, in consulting their books, 

 he was to be guided neither by adherence to the characters they 

 choose to assign to their divisions and genera, nor by attention 

 to. nature, but by random, or a certain tact only acquired after 

 much fruitless labour. The pertinacity with which the system 

 of Linnaeus has in this country been adhered to, is indeed re- 

 markable. His System of Botany was confessedly left in a more 

 finished and perfect state than his System of Zoology ; and yet 

 botanists have not ceased, from the day of his death to the pre- 

 sent time, to alter and amend that system. On the contrary, 

 our leading zoologists bound themselves in willing fetters, depre- 

 cated any alteration, however obvious, and pleased themselves 

 with laudatory paeans. Happily those days are past ; and, 

 though foreigners have led the way to better systems, and con- 

 sequently to a more accurate and extended knowledge of ani- 

 mated beings, yet the example of our present naturalists justifies 

 the belief that we shall not long be second in this race of science. 

 The system which Dr Fleming has adopted is a modification 



