UNIVALVES. TURBO. 115 



posite variety, suffice to ex\iibit the peculiarities of this 

 division. The true wentle-trap (so called to distinguish 

 it from the false) is a turbinate or spiral conical shell, 

 varying in size from a quarter of an inch to upwards of 

 two inches. The small and young shells are remarkably 

 thin, brittle, and transparent; and they generally pos- 

 sess more color than those farther advanced. The form 

 of this shell is extremely elegant; its whorls, which are 

 always gibbous or inflated, are beset, at regular dis- 

 tances, with numerous, elevated, carinated, suboblique, 

 longitudinal, continued ribs, evidently the remains of for- 

 mer mouths, the color usually of a yellowish or pinkish 

 white : however, in very young shells, the ribs are of a 

 blueish semipellucid appearance, having the interstices 

 between them of a deep brown cast, which, probably, 

 proceeds from a sort of epidermis, rather than a local co- 

 loring. There are said to be two varieties of the real 

 wentle-trap, one having only eight whorls, and perforat- 

 ed; the other having ten whorls, and imperforate: they 

 :dso inhabit different places, one, it is said, coming from 

 Barbary,the other from Coromandel. The value of these 

 shells varies in proportion witli their degree of perfec- 

 tion and size, and they have been sold from ten shillings 

 to fifty pounds. 



This slicll possesses a striking peculiarity, which con- 

 sists in its being entirely destitute of a pillar or columella 

 to connect its whorls; a circumstance so thoroughly op- 

 posed to the regular structure of all other turbinate shells, 

 must, of course, have created considerable doubt as to 

 which genus it ought to be classed in ; and some au- 

 thors have made no scruple to place it among the scrpu- 

 lap or worm shells. 



The false wentle-trap, Turbo clalhrus, is easily dis- 

 I 2 



