46 University of Michigan 



the spiral sculpture is conspicuous. Third and fourth whorls 

 (young shells) : with delicate but high, slightly undulate, 

 widely-spaced, growth costulation, which forms sutural but- 

 tresses distinctly reminiscent of T. plicatula; spiral sculpture 

 indistinct. Umbilicus : subrimate, more open than in rupis or 

 muskusi. Aperture : ovoid, with long axis almost parallel to 

 that of the shell ; internally light buff to deep orange, bordered 

 with white callus. Peristome : simple, sharp, almost or quite 

 entire ; very slightly produced into parietal angle, where it is 

 commonly double; thickened internally by white, rounded 

 callus, which is always continuous in adult shells. 



Operculum: 31/4 whorls: calcareous plate heavy (for the 

 section) and distant from the horny base; outer surface con- 

 cave at the nucleus, but with the last whorl quite markedly 

 convex along a line parallel to the palatal edge. 



Radula : quite similar to muskusi. 



Measurements 



Shell Aperture Whorls 



alt. maj. diam. alt. diam. 



aurayitius Wood 

 from legend (1828) 12.7-19.0 



from figure (1828) 14.9 53( 7.9) 37(5.5) 80(4.4) 514 



aurantiacum Sowerby 



from figure (1843) 18.1 49( 8.8) 37(6.6) 77(5.1) 5l^ 



versicolor Pfr. 



from figure (1846-9) 17.1 57(9.8) 38(6.5) 83(5.4) 4% 

 carneum Pfr. 

 from figure (1846-9) 16.7 66(11.0) 43(7.2) 78(5.6) 4% 



B2. Quite abundant (195 specimens collected). As it is very probable 

 that the vicinity of Kralendijk is the type locality of this species, these 

 specimens, from near the shore just north of town, are taken as topo- 

 typical material (see Table V). 



Bl. Common (134 specimens). Very similar to the preceding lot, but 

 with the sculpture of the last whorl even more reduced. In some speci- 

 mens, the growth threads are so broad and low as to coalesce and render 

 the surface of the last whorl almost smooth. 



B3a. Abundant (105 specimens). Very similar to B2, but attain a 

 somewhat greater size. 



B4. Abundant (32 specimens). Very similar to B3a. 



B5. Very common (19 specimens). Very similar to Bl. 



