98 DESCRIPTION OP NEW 



distribution, which had attracted attention, as it is the only species 

 which has been observed on both continents. Its discovery, now, in 

 the Columbia River, adds much to that interest, as it proves it to exist 

 on a very large portion of the circuit of our globe. It should be re- 

 marked that the nacre of these specimens is purple, a character not 

 observed from other localities. In all other characteristics there is not 

 apparently any difference whatever. 



Carocolla Hydiana. Plate XXIII. fig. 73. 



Testa orbiculata, utrinque convexa, subfusca, minuth granulatd, lath umbilicata ; anfrac- 

 tibusquinis; apertura subtriangulata, plicis quaternis incequaUbus coarciata; marginibus 

 connexis, rejiexis, subrufis. 



Shell orbicular, on both sides convex, brownish, minutely granulated, widely umbi- 

 licale ; whorls five; aperture sublriangular, contracted, with four unequal folds; mar- 

 gin continuous, reflected, reddish. 



Hab. near Porto Cabello, S. A. J. H. Gibbon, M.D. 



My Cabinet. 



Cabinet of Mr Hyde. 



Diam. 1-9, Length -9 of an inch. 



Remarks I owe the possession of this fine shell to the kindness of 



Dr Gibbon. It resembles so closely C labyrinthus (Lam.), that I have 

 had some hesitation in proposing it as a new species. There appears, 

 however, to be a diflference in the form of the mouth, in the number 

 of the teeth, and in the surface being minutely granulate. The figure 

 in Wood's Catalogue {H. plicata, No. 27), is no doubt intended to re- 

 present Lamarck's labyrinthus, but the lower part of the mouth seems 

 to be represented by three distinct folds. In some specimens of our 

 shell the fourth tooth is wanting, and I presume this is owing to its 

 immaturity. I have great pleasure in dedicating this species to my 

 friend William Hyde, Esq. 



