Mr. W. Clark on the Littorinidse. 355 



ment to the advancement of science, because in many instances 

 it destroys every attempt at identity, and renders our books 

 bulky and expensive by the insertion of worthless synonyms, 

 which have no existence as objects ; and every writer feels obliged 

 to notice all, because he has not the means of separating the ri- 

 gorously defined and well-founded species from the pseudo and 

 unsubstantial articles. It results from this false position of 

 the science, that when a student, with his object in hand, con- 

 sults the authorities, he finds ten or twelve 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 per- 

 plexities, which he, as a tyro, has neither time nor inclination to 

 unravel. 



The unsatisfactory state of this bran eh of natural history ori- 

 ginates in the practice of determining specific distinctions from 

 the shell or a half of the animal ; these are consequently arbi- 

 trary 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 sup- 

 posed difficulties of procuring living objects for examination, and 

 a disinclination to enter into the imaginary repulsive details of 

 dissection and anatomical inductions ; every day^s experience di- 

 minishes these obstacles. Naturalists may be assured that every 

 attempt to establish specific identity, without taking into account 

 both tlie hard and soft parts of the animal, will be unsatisfactory 

 and deceptive. The unpleasant operations of anatomy to per- 

 sons of great sensibility may often be dispensed with, and in the 

 majority of cases of specific discrimination are unnecessary. 



Every person, even ladies, can deposit animals in sea- water and 

 describe their habitudes and external organs, as the head, ten- 

 tacula, 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 consequently remove the incon- 

 veniences of the arbitrary creation of species on conchological 

 bases. 



I see with pleasure that the system I advocate has received a 



23* 



