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LETTER XXIV. 



THE CONCHOLOGIST'S NOMENCLATURE. — THE ACEPHALOUS 



MOLLUSCA. 



Without a collection of shells you will never become a 

 good conchologist. The collection need not be extensive 

 nor rich in rarities, but it should include specimens illustra- 

 tive of the families and principal genera ; and, that it may 

 fulfil its object, these specimens must be named by your own 

 study. The aid of figures ought at first to be rarely and 

 reluctantly required. The adage that the eye is a readier 

 teacher than the ear, is only partially applicable to objects 

 of science, for no figure can represent the object in all its 

 aspects, If by the aid of the artist we gain a certain amount 

 of knowledge readily, we as certainly lose the benefit re- 

 sulting from the habit of correct analysis, which the com- 

 parison of the object in hand with the description is so well 

 calculated to teach. I have noticed that the student who 

 ever resorts to figures, and depends upon them for the iden- 

 tification of his specimens, commits not only many errors, 

 but soon becomes incapable of enduring the patient criticism 

 which is necessary to ascertain the station and name of nearly 

 allied or abnormal species ; and his study, giving no aid to 

 mental culture, loses much of its attraction. Hence, such a 

 student either soon forsakes the pursuit, — it is too facile for 

 continuous interest, — or he lands in mere amateurship. To 

 make your choice pleasant and enduring, you must go deeper 

 and master principles and details, and give an importance to 

 the least of them. You must examine for yourself, and 

 learn the luxury of solving difficulties. Do not, therefore, be 

 seduced by the prevalent use of " Illustrations " to become 

 an iconologist ; but let your vade-mecums be the descriptive 

 works of such authors as Linnaeus, Otho Fabricius, Muller, 

 and Montagu. 



To understand the descriptions of these masters of our 

 science, you must, of necessity, learn the peculiar language 

 in which they are written, — the meaning of the words they 

 have invented or applied, to designate the exterior organs of 

 the animals in question, and their varied configuration and 

 sculpture. In conversation, you may hear people complain 



