Mr. W. Clark on the Littorinide. 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 obhged 
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 branch 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 the 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 ereation of species on couchological 
bases. 
I see with pleasure that the system I advocate has received a 
23% 
