BRITISH MARINE TESTACEOUS MOLLUSCA. 
PRADA 
CLASSIFICATION. 
Ir will be convenient, with reference to this work on the 
British Marine Testaceous Mollusca*, that a synopsis of the 
classification of the whole tribe should be submitted, accom- 
panied by a short analysis, that the meidents and position 
of any particular family may at once be examined. Most 
naturalists have their own plan of distribution with respect to 
natural order; perhaps, then, I shall not incur the imputation 
of an unmeasured presumption, if I venture to offer a sketch 
of mine, founded on forty years’ sedulous investigation of our 
indigena. I have not the vanity to suppose that my scheme 
is superior to the methods of my brethren; but it is novel, 
and exhibits, as I think, a progressive advancement of animal 
organization and harmony of arrangement from the begmning 
of the class to its termination, by which groups of similar 
affinities are insensibly united as far as is possible, and suc- 
ceed each other, on the basis of external and internal anato- 
mical considerations, 
These memoirs are the result of numerous visits to the 
* The main object of this work is the description of the animals of the 
British marine testaceous Mollusca, and though a few of the freshwater 
and land families and genera are mentioned, it is only incidentally, and to 
fill up the outline of the British classification, but no account of their 
species will be given. 
B 
