TROCHUS. 313 



inner one on the left irregularly pectinated or fringed, and the 

 other plain but folded; each of these lappets is continued 

 along the upper part of the foot, where it forms a jagged crest : 

 head semicyk'ndrical and short, wedge-like at the extremity, 

 streaked across, and notched at the front edge ; veil composed 

 of two membranous and fringed lobes or expansions above the 

 tentacles, one on each side of the intermediate space : tentacles 

 slender and bluntly pointed; they are thickly covered with 

 short cilia, and marked with purplish rings, which are alter- 

 nately large and small, and often interrupted or broken as well 

 as scalloped ; these rings somewhat resemble the joints of an 

 Equisetum : eyes rather large ; stalks angular and yellow : foot 

 rather oval than oblong, sparingly granulated on the upper 

 part and sides ; edges fringed with minute cirri ; sole slightly 

 furrowed down the middle : appendages 3 on each side, the 

 hinder two being rather close together, and the other in the 

 middle of the lateral space ; they are indistinctly annulated 

 and slightly setose ; each is encircled at its base by a jagged 

 sheath, and provided with a small whitish and raised tubercle 

 on each side, which issues out of the foot-crest. 



SHELL more depressed than T. cinerarius, and (although the 

 base is flatter) never inclined to a pyramidal form ; the spiral 

 ridges are sharper and fewer, especially in the young : the 

 colouring is different ; both have a similar kind of marking, 

 but in the present species the longitudinal rays or streaks are 

 red, besides being broader and not half so many as in the other 

 species; and they are sometimes zigzag, instead of being 

 broken into spots or interrupted by the sculpture; this is 

 striped and the other lineated ; just within the outer lip are 

 two borders, one of yellow and the other of green, variegated 

 by red spots ; this edging is minutely tubercled, like shagreen. 

 L. 0-55. B. 0-7. 



Yar. 1. atro-purpurea. Always depressed and of a dark- 

 purplish hue. 



Yar. 2. decorata. More conical, and speckled like the 

 variety variegata of the last species. 



Yar. 3. Agathensis. Smaller, with the spire more raised, 

 less angular, and somewhat glossy on the underside ; colouring 

 purple instead of red ; base usually not umbilicate (except in 

 the young), but occasionally perforated. T. Agathensis, Recluz, 

 in Rev. de Zool. for 1843. 



VOL. III. P 



