UNIVALVES. — TURBO. 119 



The varieties of the T. phasianus have been exceedingly 

 rare : — there is no other species in this genus which pre- 

 sents so much beauty and diversity as the Pheasants. They 

 are found at Van Dieman's Land, and other islands of the 

 South Seas. 



The next variation consists in the pillar of some species 

 being perforated or umbilicated. The T. pica (as being 

 the most known and easiest procured) will be the best to 

 refer to as an example. The T. margaritaceus and the 

 T. argyrostomus also belong to this division. 



Another division is composed of those species that are 

 less solidj and cancellated. The wentle-trap (from the 

 German, windle-treppe, or winding-staircase), one of the 

 most beautiful as well as the rarest of the genus, will suf- 

 fice to exhibit the peculiarities of this division. The true 

 wentle-trap is a turbinated 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 generally possess more colour, (usual- 

 ly of a yellowish or pinkish white), than those farther ad- 

 vanced. The form is extremely elegant; its whirls, which 

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

 tances, with numerous, elevated, carinated, suboblique lon- 

 gitudinal, continued ribs, evidently the remains of former 

 mouths. In very young shells, the ribs are of a blueish 

 semipellucid appearance, and have the interstices of a deep 

 brown cast, occasioned, probably, by a thin epidermis, ra- 

 ther than a local colouring. There are said to be two va- 

 rieties of the real wentle-trap, one having only eight 

 whirls, and perforated; the other having ten whirls, and 

 imperforated : they also inhabit different places ; one, it is 

 said, comes from Barbary, the other from Coromandel. 

 This species possesses a striking pecuharity, which con- 



