208 AMERICAN JOURNAL 



thousand species. This work is based on my ' List of Genera,' 

 and on the ' Genera' of Messrs. Adams, and is certainly one of 

 the cheapest and most useful manuals for the use of the shell- 

 collector and malacologist that have yet been compiled. 



The collection of shells exhibited in the British Museum first 

 showed to the conchologist and the palaeontologist the advantage 

 of the more scientific arrangement of the mollusca and their 

 shells into smaller groups, and according to the structure of the 

 mollusca and their teeth and anatomy, the opercula, and the 

 shells. 



The dealers were at length convinced (as Humphrey had been 

 many years before) that the use of a larger number of genera 

 extended their trade, as it produced a crop of customers (besides 

 those who merely bought shells for their beauty or variety) who 

 purchased the less conspicuous shells for the purpose of obtain- 

 ing one or more examples of each genus ; and the general stu- 

 dents were gradually induced to adopt the improvement. 



The students of fossil shells seem inclined to lag behind the 

 knowledge of the day. They have some excuse, as fossil shells 

 do not afford them all the means of study to be obtained from 

 recent species ; but they might do much more than they have 

 done, and they can never derive all the advantages in geology 

 that the study of the fossil mollusca can afford them until they 

 study their shells with the same attention as has been applied to 

 the recent species, and revise the heterogeneous genera into 

 which they are now grouped. Mr. Searles Wood, long ago, set 

 an example of the right course to be pursued in his paper " On 

 the Crag Fossils;" but few have followed him. I think that the 

 faith they place in Woodward's ' Manual ' is one of the causes 

 of their want of progress. 



The iconographers, such as Lovell Reeve and Mr. Sowerby, 

 have published illustrated monographs of many genera of shells 

 on the modern system ; but unfortunately they do not seem to 

 think it is enough to figure each species, but they figure even 

 slight varieties under the name of species. This has rendered 

 their works so expensive that they are only to be regarded as 

 works of luxury for the libraries of the rich; while the number 

 of the varieties they figure, and the want of system in the ar- 

 rangement of the species, render them very difficult to use by 

 the scientific conchologist. You may almost buy a good collec- 

 tion of shells for the price of these works ; and every one would 

 learn more from the shells themselves than from works on them 

 of such ah unscientific character." 



