382 CALLIOSTOMA. 



middle of it. Umbilicus none ; whorls flattened above between 

 periphery and suture ; base rather rounded. 

 Alt. 5-0, diam. 3-75 mill. {Dull.) 



Off Havana, in 450 fms. 



Calliostoma corbis Dall, " Blake " Gasteropoda, p. 365, t. 33, f. 1. 



This species was at first confused with C. tiara Watson, which has 

 not the continuous strong network, and in which the nodules which 

 represent the intersections are of an imbricated character. The 

 strong carina in C. corbis forms the periphery, in C. tiara the 

 homologous spiral is comparatively faint and a little above the 

 periphery. In C. tiara also the c nter of the base is indented, 

 almost unibilicated, which is not the case in C. corbis. The latter is 

 a more solid shell, and the curious callosity on the pilhir does not. 

 occur in any of the specimens of C. tiara I have seen. (Dull.) 



C. AURORA Dall. PI. 48, fig. 10. 



Shell delicate, nine whorled, acutely pointed ; above with a color 

 varying from light pink to straw color ; below light cream color, 

 the sharp peripheral carina lighter than the rest of the upper sur- 

 face ; general outline from nucleus to basal periphery somewhat con- 

 cave ; base concavely excavated within the margin, slightly convex 

 toward the center ; nucleus whitish, smooth ; whorls gently rounded, 

 closely appressed to the almost invisible suture and excavated in 

 front of it ; the last whorl flatter above, more rapidly enlarged at the 

 periphery. Sculpture of small regular waves on the carina, about 

 six in a space of 5"0 mill., giving a minutely scalloped outline ; be- 

 hind this a strong nodulous thread, revolving like a string of small 

 uniform beads ; then a more slender thread more finely beaded ; in 

 all eleven regularly alternating revolving threads at the beginning 

 of the last whorl ; this sculpture is very uniform all over the sur- 

 face ; base polished, smooth, except for two or three faint beaded 

 lines and grooves about the pillar, and faint longitudinal and trans- 

 verse growth markings ; aperture nearly twice as wide as high ; 

 lower lip with a beautiful concavely arched outline, falling much be- 

 hind the upper one ; margin simple, except for sculpture marks ; 

 pillar short, arcuated, pearly, simple, ending in a slight point. 



Alt. 21-0 ; diam. 26-5 mill. (Dull.) 



Barbados, in 140-576 fms. 



Calliostoma aurora Dall, " Blake " Gasteropoda, p. 366, t. 37, 

 f. 2. 



