354 Mr. W. Clark on the Littorinide. 
inclined to reduce the true specific types to L. neritoides, L. lit- 
torea, L. littoralis and L. rudis.” 
My views being thus supported, I send forth without besita- 
tion these observations made long ago, and I feel gratified that 
my investigations of this tribe have received the corroboration 
enunciated by that eminent Professor. 
Before I give the descriptions of the types of the genera of the 
Inttorinide, 1 will make some remarks on the prevalent practice 
of naturalists to create species from mere varieties: this anxiety 
can only be attributed to their wish to extend our knowledge of 
new and interesting objects: that these views are desirable and 
laudable cannot be questioned, but it is to be feared that the zeal 
of these gentlemen, combined with the ardour of rivalry in the 
race with their brethren in the same pursuits, have been the 
cause of a departure from those principles and laws which are 
considered indispensable to arrive at just conclusions in the esta- 
blishment of genera and species; or in other words, in laying 
down the true bases of the differential features of the families, 
genera and species of a class, so as to enable the student to de- 
posit his objects with certainty in their natural position, and to 
distinguish them from others, however numerous, of the same 
family, by concise and well-defined specialties. If these rules 
were rigorously attended to, we should have fewer complaints of 
the almost impossibility of identifying many of the objects of 
natural history. The inconveniences that have arisen from the 
neglect of these precepts are so great and pressing, that I pro- 
pose to attempt to point out their origin, and suggest a remedy 
as far as regards malacology and conchology, and to evidence 
and illustrate my arguments by references to the present state of 
certain groups of the Mollusca. 
If conchologists are determined to form numerous species from 
* mere varietal conchological indicia, they must have their way, but 
malacologists will not concur with them to give a dozen names 
to the same animal. These gentlemen cannot escape having the 
phrase “ Dies docebit ” verified ; the day of retractation will as- 
suredly arrive; it will therefore be better for the interests of 
science and their amour propre, at once to apply the remedy for 
this singular creative monomania, 
. . » “O medici mediam pertundite venam.”’ 
I apologise for my irreverent quotation, and trust I may claim 
for this once, 
ih eo Se beriusier 
Dixero quid, si forte jocosius, hoc mihi juris 
Cum venia dabis.”’ 
The practice I have just described is fraught with great detri- 
