MOLLUSCA. 29 
served that, in some genera, the valves do not close or unite 
all round, but that, at certain places, the shell remains in 
part open. Such shells, in modern language, are said to 
gape. 
The system of the celebrated Linnzeus, which ought now 
to be mentioned, is too well known in this country to de- 
serve particular notice. In many of the other departments 
-of Zoology he effected the most important alterations ; but 
his attempts to reform the science of conchology, were far 
from being equally successful. ‘To the subject he never 
was much attached, nor does he appear to have availed him- 
self sufficiently of the labours of those authors whom we 
nave mentioned, and .of others who preceded him. The 
primary divisions which he employed, were those which 
Major had established, and his genera, with a few excep- 
tions, were those in common use. His merit as a concho- 
logist rests entirely on the accurately defined terms, the 
concise specific characters, and the convenient trivial 
names which he employed and introduced. The particu- 
lar consideration of the Linnzan genera, and the subse- 
quent changes which have been introduced into them, will 
form the subject of a separate section. 
For some time after the publication of the Systema Na- 
ture, the illustrious Swede enjoyed a very dangerous repu- 
tation. All his arrangements were regarded as of such high 
authority, that it was considered as impious to attempt to in- 
troduce any change; so that conchology, and along with it 
the study of the mollusca, according to the artificial method, 
remained a long time stationary. At last in France, a coun- 
try which refused to submit to the fetters of the Linnazan 
school, several new systems were proposed, which had for 
their object the restoration of those well-founded genera, 
