88 UNIVALVES. TURBO. 



pie. The Turbo Margaritaceus or Pearly Turbo, the 

 Turbo Argyrostomus or Silver Mouth, and the Turbo 

 Delphinus or Dolphin Shell, also belong to this division. 



A further alteration or variation takes place in those 

 species that are less solid, at the same time that they are 

 caucellate. The Wentle-trap (from the German Windle- 

 treppe, or Winding-staircase) as being one of the most 

 beautiful as well as rarest shells known, will, with its op- 

 posite variety, suffice to exhibit 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 remarka- 

 bly 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 

 also inhabit different places, one, it is said, coming from 

 Barbary, the other from Coromandel. The value of these 

 shells varies in proportion with their degree of perfection 

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

 jfifty pounds. 

 This shell possesses a striking peculiarily, which con- 



