INTRODUCTION, Panama Shells. 23 



this extreme low water mark, where the air will but slightly 

 reach the animal every fortnight, and that of a few feet high- 

 er, whence the water wholly recedes twice- every day. 



Having an opportunity of shipping the collections, which 

 filled eight cases, we wrote the bills of lading, Jan. 3, 1851, 

 and the next morning left Panama for Chagres and Jamaica. 

 It was not until Aug. 14 that the cases arrived at their des- 

 tination. After assorting the shells, we find 38.920 speci- 

 mens of 376 species of Gasteropoda, 2.860 specimens of 139 

 species of Acephala, and 50 specimens of 1 species of Braoh- 

 iopoda : total, 41.830 specimens of 516 species of Mollusks. 

 The number of specimens of each species is mentioned in the 

 following pages. It is scarcely necessary to add that we have 

 stated the total number of individuals, to give approximately 

 an idea of the relative abundance of the species at the time 

 and places mentioned, and not of such specimens as amateurs 

 would pronounce ' good shells.' 



In the following catalogue our principal object, after the 

 enumeration of the species, has been to collect the statement 

 of various writers concerning the habitats and stations of the 

 species. Where two names of persons follow the habitat or 

 station, the first is usually that of the person who collected the 

 species, and is followed by an exclamation mark ! The second 

 name is that of the author who is quoted. The (!) after a 

 single name indicates that the author was also the collector ; 

 but the absence of this mark indicates that the testimony is 

 not original, whether one or more names are cited. 



It will be seen that for a knowledge of the stations we 

 are chiefly indebted to Mr. Cuming. 



In appending synonymy, we have quoted nothing. The 

 references have been made chiefly as vouchers for the accu- 

 racy of the names of the species, and as means of detecting 

 errors. A subordinate object has been the convenience of 

 those friends among whom the duplicate specimens may be 



