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others so nearly resembling his, that he becomes bewildered in 

 the mazes of distinctions, often without differences, despairs of 

 identifying his object, and perhaps retires altogether from a 

 rational and highly important pursuit, under the idea that the 

 science is full of perplexities, which he, as a tyro, has neither 

 time nor inclination to unravel. 



The unsatisfactory state of this branch of natural history 

 originates in the practice of drawing up specific distinctions 

 from the shell or a half of the animal ; these are consequently 

 arbitrary and artificial ; and though, in decided forms, this plan 

 may produce correct results, it signally fails when structures 

 begin to shade into each other; then the sheet-anchor, the 

 animal, can alone solve doubts, and often shows that shells, 

 apparently well marked by specific distinction, are not in 

 reality distinct, and vice versa. 



This neglect to consult the most important, the soft parts 

 of the animal, has in some measure been occasioned by the 

 supposed difficulties of procuring living objects for examina- 

 tion, and a disinclination to enter into the imaginary repulsive 

 details of dissection and anatomical inductions ; every day's 

 experience diminishes these obstacles. Naturalists may be 

 assured that every attempt to establish specific identity, with- 

 out taking into account both the hard and soft parts of the 

 animal, will be unsatisfactory and deceptive. The unpleasant 

 operations of anatomy to persons of great sensibility may often 

 be dispensed with, and, in the majority of cases of specific 

 discrimination, are unnecessary. 



Every person can deposit animals in sea- water and describe 

 their habitudes and external organs, as the head, tentacula, 

 eyes, and how they are placed, whether at the external or 

 internal bases of the tentacula; and if on pedicles, what is 

 their proportion to the length of the tentacula; the shape 

 of the foot, operculum, the mouth, and coloration of the 

 animal, &c. ; these points, with the sculpture of the shell, will 

 in almost all cases ensure specific distinctions, and conse- 

 quently remove the inconveniences of the arbitrary creation of 

 species on conchological bases. 



I see with pleasure that the system I advocate has received 



