130 CONCHOLOGY. 



formed by gibbous whorls, unconnected by a columella, 

 gradually increasing from the apex to the base. The colour 

 is generally yellowish or brownish white. When perfect and 

 of good size, they are of great value and highly prized. 



Shell sub-turreted, the whorls of the spire more or less 

 pressed and garnished with interrupted longitudinal ribs, 

 formed by the successive preservation of the reflected mar- 

 gin of the aperture, which is small, perfectly round, with 

 edges united, thickened, and outwardly reflected ; operculum 

 horny and thin. 



Scalaria pretiosa. Scalaria varicosa. 



S. lamellosa. S. communis. 



S. coronata. S. Australis. 



S, raricosta. 



S. pretiosa. The precious Scalaria, more commonly call- 

 ed the Wentle Trap, or Winding Staircase. PI. 23, fig. 1. 



This shell has its spiral whorls separate, and appears like 

 an attenuated tube evolved round a cone ; spire detached, 

 with a deep umbilicus ; volutions connected by longitudinal 

 ribs ; body extremely ventricose ; colour cream yellow. 



S. communis. The common Scalaria, or false Wentle 

 Trap. 



More taper and elongated than the S. pretiosa. It has no 

 umbilicus, and the whorls are closely united. 



3. Delphinula. Three species. 

 A marine shell, which, like the Scalaria, has a round aper- 

 ture, but its solidity and pearly substance distinguishes it 

 from the Cyclostoma, which is terrestrial. 



Shell thick, pearly in the interior, sub-discoid or conical; 

 the spiral whorls sometimes detached, rounded, spiny, with 

 a large umbilicus ; aperture round or multrigonal, not mod- 

 ified ; edges perfectly united with a small spire, tuberculated 

 exteriorly. 



Delphinula laciniata. Delphinula distorta. 



D. turbinopsis. 



