v j INTRODUCTION. 



specimens described or figured, or to which special interest attached ; 

 and they were so disposed of as to be easily accessible and readily re- 

 cognised. The drawings relating to them had been so far finished as 

 to secure the forms and attitudes, more particularly the colours of the 

 animals, all of which greatly change after death, leaving the more 

 permanent features to be copied at leisure. The identification of these 

 shells was, therefore, very important. But it had been thought neces- 

 sary, by the Navy Department, that the boxes sent home in advance 

 of the Expedition should be opened, lest, by long packing, the speci- 

 mens might be injured. Those who performed this service were not 

 fully aware of the importance of replacing the specimens as originally 

 arranged, and hence much labour and difficulty in identifying them. 

 In many instances, the search was quite fruitless, and, consequently, 

 many drawings and descriptions were altogether rejected, and so far 

 lost. 



Still an additional difficulty arose from residing at a long distance 

 from Washington, where the collection is deposited, rendering it impos- 

 sible to have such a frequent recourse to the specimens as would have 

 greatly facilitated the settlement of questions which arose from day to 

 day. 



Notwithstanding the disadvantages under which this branch of 

 Zoology laboured, an immense mass of specimens of shells was col- 

 lected, and among them a very large number of new species, larger, 

 probably, than has ever been collected by any similar Expedition. 

 Both before and after the separation of Mr. Couthouy, a very decided 

 zeal, in the collection of shells, was manifested by both officers and 

 men, as well as by the other members of the Scientific Corps. Among 

 them must be especially mentioned, as the principal collectors : 

 Commander Charles Wilkes; Messrs. J. P. Couthouy, C. Pickering, 

 J. D. Brackenridge, T. R. Peale, W. Rich, J. D. Dana, of the Scientific 

 Corps; J. Drayton, Artist; Lieutenants C. Ringgold, A. L. Case, 

 T. A. Budd, W. M. Walker, J. A. Underwood ; Passed-Midshipmen 

 W. May, W. Reynolds, H. Eld; Midshipmen G. W. Hammersley, 

 and George Elliott, Jr.; Assistant-Surgeons J. L. Fox and J. S. 



