TROCHUS. 79 



roseate ; suture distinct, not canaliculate ; whorls 5, moderately 

 convex, encircled by lirse more or less distinctly granulate, very 

 unequal in size, numbering, on the last whorl about 14, the inter- 

 stices closely obliquely striate, and usually bearing a minute central 

 riblet ; body-whorl descending anteriorly, rounded at the periphery ; 

 base convex, the revolving lirse more superficially and much more 

 closely cut into granules than those of the upper surface, and also 

 broader, flatter, and equal in size, numbering 6 to 7, one or two 

 around the umbilicus white, dotted with yellow or reddish, the 

 remainder reddish-brown, sparcely articulated on the ribs with 

 white, sometimes radiately marked with narrow white stripes ; 

 aperture oblique, somewhat contracted, subcircular ; outer and basal 

 lips thickened, finely crenulated within ; columella oblique, with a 

 tooth-like fold above, solute, and deeply inserted upon the side of the 

 umbilicus, middle portion concave, with a reflexed subdenticulate 

 edge, ending beneath in a minute denticle ; umbilicus profound, 

 smooth and polished within, bordered by a strong rib bearing 6 or 

 7 projecting white teeth, the upper one the largest. 

 Alt. 9, diam. 12 mill. 



Andaman Is. 



Clanculus microdon A. AD., P. Z. S. 1851, p. 162. E. A. SMITH, 

 P. Z. S. 1878, p. 818, t. 50, f. 21. 



A species belonging to the group of atropurpureus, bathyrhaphe, 

 etc., including species in which the base of the columelia is scarcely 

 toothed, but passes into the basal margin in a regular curve, bearing 

 several subequal denticles, the columella above inserted upon the 

 side of the umbilicus instead of in the center of the axis as in the 

 typical Clanculopsis. From T. atropurpureus, which seems to be its 

 nearest ally, T. microdon differs in the larger size, variegated color- 

 ation, and irregularity of the spiral ribs on the upper surface. 



T. PLEBEICJS Philippi. PL 10, figs. 19-22 ; pi. 13, figs. 1, 2. 



Shell small, depressed, umbilicate, pinkish brown, gray or yellow, 

 the ribs articulated with dots of black and white, often forming 

 radiating lines above, zigzag beneath, where yellow replaces pink in 

 the ground-color ; spire low-conic, apex acute ; whorls about 5, 

 coarsely lirate, the sutures subcanaliculate ; body-whorl obtusely 

 angular at the periphery, its upper surface encircled by 4 coarse, 

 somewhat beaded lirse, the upper two contiguous, the third separated 

 by wide intervals above and below it, the fourth peripheral, usually 



