MARINE UNIVALVES 139 



ently smooth and polished, is shown under the micro- 

 scope to have fine and beautiful reticulations. The 

 spire is short, the aperture long and narrow, the canal 

 a mere notch, and the outer lip is thin-edged. Upon 

 the inner wall of the aperture is a lump of white 

 enamel, and at the base of the columella are two 

 little folds, which are referred to in the name bipli- 

 cata^ meaning twice folded. The color of the shell 

 varies much in different specimens; some are almost 

 pure white, others are very dark, but most of them 

 are dove-colored, with purple trimmings. They re- 

 semble the olives of our orchards in form and size, 

 so their name has no mystery connected with it, but 

 it was doubtless chosen by Mr. Swainson, in 1835, on 

 account of the appearance of the shells. It is only 

 fair to say, however, that back in 1789 the name 

 Oliva was applied to the large group of smooth shells 

 of which our little specimen is a humble representa- 

 tive. At the present time the genus Oliva includes 

 the larger species, which have no operculum. The 

 genus Olivella^ meaning "little olive," includes the 

 smaller species, among which the specimen that we 

 are now considering is classed, and which proves its 

 right to be there by the presence of an operculum, as 

 we have already indicated. Concerning these shells 

 Dr. Paul Fischer remarks in his Manuel de Conchy- 

 liologie, "Les coquilles sont de petite taille; I'une 

 d'elles (O. bipUcata^ Sowerby) est recherchee par les 

 indigenes de Californie, qui la polissent, la percent, 

 I'emploient comme ornement ou monnaie sous le nom 

 de Colcol. On en trouve d'assez grandes accumula- 

 tions dans les tumuli." From these words I under- 



