ADVERTISEMENT. VU 



Arrangement of Molluscous Animals ; but, 

 whatever merits that system may possess, he 

 cannot allow himself to become, even un- 

 intentionally, the instrument of dissemina- 

 ting principles of classification which, in his 

 opinion, must eventually close the door 

 against all who cannot devote their whole 

 time and talents to the attainment of natu- 

 ral science. Upon this ground, therefore, 

 he continues his adherence solely to the 

 Linnsean genera, admitting, as he has done 

 before, that there are some deficiencies in 

 the system which might be advantageously 

 supplied without losing sight of its simpli- 

 city. 



