MOLLUSCA. 27 
to the different forms of the shell, is unquestionably the most 
obvious and the most ancient method. It was first employed 
by Aristotle, the father of natural history, and even in the 
present day its admirers are warm in its praise. It is with 
great propriety termed the artificial method, because the 
characters employed have but a remote relation to the more 
important functions of the animal. This eminent philoso- 
pher had the merit of forming the great divisions of wnival- 
ves and bivalves. He likewise separated the turbinated uni- 
valves from such as have but an imperfect spire, and formed 
many genera, or rather families, still retaining the names 
which he imposed. 
The progress of the study of the shelly mollusca (the 
naked kinds being in a great measure neglected,) made very 
little progress for many ages after Aristotle had published 
his method of arrangement. Indeed, the first work of this 
sort which claims attention, is the Dietionarium Ostracolo- 
gicum of Major, which was published in 1675. To him we 
_ are indebted for the threefold division of shells into wnz- 
valves, bivalves, and multivalves, and for an explanation of 
the terms then employed by conchologists. 
In the same career, but with more brilliant success, Lan- 
gius followed, and, in 1722, published his Methodus Nova 
Testacea Marina in suas Classes, Genera et Species distri- 
buendi. The following character is given of this work by 
the intelligent and industrious authors of the Historical Ac- 
count of Testaceological Writers. (Linn. Trans. vol. vii- 
p. 156.) “ After having noticed a multitude of mere de- 
scribers, we now come to an author who is not undeserving 
of the title of a scientific one, and whose system, so far as 
marine ¢estacea are concerned, (and of these alone he treats) 
certainly glances at the great clue to simplicity, which was 
