108 UNIVALVES. TURBO. 



chrysostomus, X- pagodus, T. calcar, and T. smaragdus; 

 to vvhicli may be added, the T. cochlus, T. cornutus, T. 

 nigerrimus, T. marmoratus, and T. olearius, the two latter 

 of which sometimes attain a large size. 



The varieties of the T. phasianus and T. pulcher have 

 been exceedingly rare: — there is no other species in this 

 genus which presents 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, the T. ar- 

 gyrostomus, and the T. delphinus, also belong to this 

 division. 



Another division is composed of those species that are 

 less solid, and cancellated. The wentle-trap (from the 

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

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

 with its opposite variety, suffice to exliibit the peculiari- 

 ties of this division. The true wentle-trap is a turbinat- 

 ed 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 transpa- 

 rent, and generally possess more color, (usually of a yel- 

 lowish or pinkish white), than those farther advanced. 

 The form is extremely elegant ; its whirls, which are al- 

 ways gibbous or inflated, are beset, at regular distances, 

 with numerous, elevated, carinated, suboblique, longi- 

 tudinal, continued ribs, evidently the remains of former 

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

 ish semipellucid appearance, and have the interstices 

 of a deep brown cast, occasioned, probably, by a thin 



