ON MOLLUSCA. 149 
being placed in his order zoophytes, class vermes, and the 
conchyliferous, in his third order of the same class, under the 
name of testacea. Though he does not yet distinguish his 
different genera but by a very small number of characters 
derived from the shell, he nevertheless cites the naked animal, 
which he supposed to belong to it, and which he had placed 
in his zoophytes, but that evidently in an accessory manner. 
But in the tenth edition we find considerable augmenta- 
tions, and still more in the twelfth, which may be considered 
as having received the finishing hand of its celebrated author. 
The class vermes is there divided into five sections, the se- 
cond of which has the name of mollusca, and contains eight 
genera of the true mollusca, ascidia, limax, aplysia, doris, 
tethis, sepia, clio, and scyllea. The third is almost entirely 
consecrated to the testacea, divided into multivalves, bivalves, 
and univalves. 
In the characters of their genera, however, Linnzus always 
confines himself to the citation of an analogous naked mol- 
luscum; so that if the work of Adanson had any influence 
over the last editions of the Systema Nature, it was only in 
the more numerous division of the genera of shells, and in 
their better circumscription. But it had little real effect on 
the part relating to animals. Thus we find among the mol- 
lusca of Linneus some which are articulated and others 
which are radiated animals. In his testacea also there are 
several inconvenient approximations. 
Though the French zoologists whom we have mentioned 
may be considered the founders of a scientific arrangement of 
these animals, yet they paid no attention except to the ex- 
ternal parts of the animal body inhabiting the shell, and 
moreover, took no notice whatever of the naked mollusca. 
Nevertheless, the impulse given to his age throughout 
Europe, by the system of Linnzus, and in France by the 
writings of Buffon, occasioned many naturalists to publish 
