186 SISTRUM. 



R. TUBERCULATUS, Blahiv. PL 57, figs. 218, 220. 



Yery variable in outline, some specimens being much shoul- 

 dered, with short spire, others ovate with longer spire. Closely 

 allied at first sight to R. morus but dark olive-brown, the tuber- 

 cles darker or black, and surface closelj' covered with revolving 

 striae instead of the single small rib between. each row of tuber- 

 cles as in R. morns. The aperture is dark brown or black, the 

 teeth and columella partially white. Length, '75-1 inch. 



Japan ; Philippines to Sandwich Isles. 



The external resemblance of this species to Purpura musiva, 

 Kiener, is very great ; the genuine purpuroid aperture of the 

 latter will serve to distinguish them. 



The animal is described b}^ Gould in the Mollusca of Wilkes' 

 Exped. as being deep grass-green ; with the mantle, locomotive 

 disk and tentacles light sea-green finely dotted with white. 



R. Anaxeres, Duclos. PI. 57, fig. 219. 



The coloration is the reverse of that of R. tuberculatus ; that 

 is, the shell is dark and the nodules light — frequently nearly 

 white. Length, •4--5 inch. 



Natal; Solomon's Isles ; Australia; Paumotus, 



Is possibly not adult, and is related in sculptui-e to R. morus, 

 but otherwise more closely to R. tuberculatus. 



R. MARGINATRA, Blaiuv. PI. 57, figs. 221, 222, 225-229. 



Shell very variable in outline, cancellated b}^ revolving and 

 longitudinal ribs, b}' which the surface is broken up into tuber- 

 cles ; most prominent as revolving series and usually incisely cut 

 by revolving striae wiiich, in the interstices of the nodular series 

 become scabrous. Brownish, the nodules usuallj^ darker. Aper- 

 ture bluish within, with revolving raised chocolate lines which 

 terminate in four or five white or fulvous tubercles upon the 

 thickened lip ; lip and columella stained with chocolate. 



Length, •75-1 inch. Australia; Central Polynesia. 



The type (fig. 225) is a j^oung shell ; the adult is Purpura 

 marginalbum., Blainv. (figs. 221, 226). I cannot distinguish P. 

 canceUata, Kiener (fig. 227) nor Ricinula fusca, Kuster (fig. 222). 

 Pease acknowledges the difficulty of separating his Sistrum 

 affine (fig. 228). and von Martens has already considered it a 



