156 FISSURELLA. 



May be known by the conical form and purple-red coloration. 

 Carpenter's citation of this form from Mazatlan needs confirmation. 



F. CLYPEUS Sowerby. PI. 60, fig. 82 ; pi. 31, fig. 20. 



Shell ovate, rather thick, depressed, obscurely radiately ridged, 

 ridges distant, obsoletely prickly nodose ; orifice oblong-ovate, rather 

 small ; whitish peculiarly rayed in a reticulated manner with burnt 

 black ; interior margin tessellated, (five.) 



St. Elena, West Columbia. 



F.clypeusSow.P. Z. S. 1834, p. 128; Conch. Illust., f. 77. 

 EEEVE, Conch. Icon. f. 76. SOWERBY, Thes. Conch, iii, p. 185, f. 63. 



F. MURICATA Reeve. PI. 39, fig. 5. 



Shell ovate, conical in the middle, rather depressed at the sides, 

 radiately, somewhat obscurely ridged and striated, ridges prickly 

 nodose ; orifice oblong, sides excavated in the middle ; blackish- 

 purple, whitish around the orifice, (five.) 



Habitat unknown. 



F. muricata RVE. Conch. Icon. f. 103. SOWB. Thes., p. 186, f. 68. 



F. VOLCANO Reeve. PL 62, figs. 16, 17, 18. 



Shell oval, usually a little narrower in front, the.orifice a little in 

 front of the middle, oblong, often obscurely tripartite, about one- 

 eighth the length of the shell ; surface with radiating unequal rib- 

 lets, often subobsolete. Color pink- ashen with 13 to 16 purplish 

 rays, often speckled near the summit. Inside white, smooth, fre- 

 quently with a pink line bounding the callus around the perfora- 

 tion ; border narrow, dark, alternately pink or purple and gray. 



Length 24, breadth 18, alt. 11 mill. 



Length 25, breadth 17, alt. 10 mill. 



San Hippolite Point, L. Cal. to Sta. Cruz, Cal. 



F. volcano RVE. Conch. Icon. f. 2, 1849. SOWERBY, Thes. Conch, 

 iii, p. 192, f. 87. And of authors generally. F. ornata Nuttall MS. 

 in CARPENTER, P. Z. S. 1856, p. 222. 



A pretty species, abundant on the coast of California. Beach- 

 worn shells are pink with red rays, but fresh specimens have a dul- 

 ler ashen color. There is considerable variation in the prominence 

 of the radiating riblets. 



