476 Analj/tical Notices of Books, 



described ; many of these are however found only in the fossil 

 state, and have been already admirably illustrated by Brocchi. 

 The novelties are very numerous, and 183 of them are well 

 figured in the twelve plates which accompany the volume. In 

 the discrimination of genera M. Risso has laboured hard, having 

 added to those of his predecessors, which he has adopted in their 

 most restricted signification, upwards of fifty new ones. Of these 

 several are established from the MSS. of our respected and 

 talented countryman Dr. Leach. Where subdivision has once 

 been carried to the extent which is now almost universally re- 

 ceived among Conchologists, we are aware that consistency almost 

 requires that it should be had recourse to even still more freely ; 

 but we fear that our authour has here advanced with too rapid a 

 stride. The genius of the age will scarcely keep pace with him, 

 and Nature herself, we apprehend, will not uniformly agree with 

 his conclusions. The points on which he founds his generic dis- 

 tinctions are, in our opinion, frequently too minute ; in some in- 

 stances he appears even to have created a genus from a young 

 shell, which, in its perfect state, is referred to an older and re* 

 ceived division. We speak with little doubt on this point, al- 

 though we have not the specimens before us, by which alone our 

 opinions could be verified. An opportunity of determining their 

 accuracy will however be afforded to the Conchologists of Paris, 

 to the museum of which city M. Risso states his intention of for- 

 warding specimens of all his new species : an admirable plan, the 

 general adoption of which would prevent the endless confusion 

 that results from the want of original types, ticketed by the au-< 

 thours themselves, of the objects indicated by them. 



The Annelida described amount to eighty-two, including three 

 new genera. 



