MUSEUM OF COMPARATIVE ZOOLOGY. 47 



Calliostoma Yucatecanum n. s. 



Shell belonging to the group of ft Palmeri Dall, ft eximium Rve., and C. lima 

 of the western coast of America. Shell depressed conic with a rather acute 

 apex and six whorls ; nucleus white, delicately sculptured ; remainder of shell 

 whitish with faint streaks of hrown transverse to the whorls, arranged so as to 

 present the appearance of seven brownish streaks radiating from the apex ; 

 other dots and streaks of brown irregularly distributed ; upper side of whorls 

 with one smooth revolving keel nearly midway between the sutures, but a 

 little nearer the periphery ; this gives the whorls a somewhat tabulated aspect ; 

 above this on the last whorl are four smaller more or less beaded or crenulated 

 keels, below it are two without nodosities, reaching the gently rounded periph- 

 ery ; between these are intercalary threads or grooves ; base supplied with nine 

 rounded revolving ribs, those nearer the umbilicus with a tendency to 1 nail- 

 ing ; interspaces about as wide as the ribs, which are crossed by slight eleva- 

 tions due to lines of growth ; umbilicus perforate, bordered by a strong white 

 rib, inner walls smooth or transversely striate ; pillar emarginate, twisted, not 

 thickened, ending in a rounded lump above the basal margin of the aperture ; 

 the latter oblique, subrectangular, nacreous, sharp-edged, crenulated by the 

 ribs. Operculum as usual in the genus. Alt. 7.0. Basal diani. 7.0. Diam. 

 of aperture, 4.0 ; of umbilicus, 1.0 mm. 



Yucatan Strait, 640 fms. 



Calliostoma echinatum n. s. 



Shell small, white, acute-conical, in general resembling ft sapidum, but less 

 stout and solid and with wholly different sculpture ; whorls six, somewhat ap- 

 pressed toward the apex ; nucleus smooth, semi-transparent, inflated, shining, 

 remainder of shell opaque white with the following sculpture; on the upper 

 whorls, four revolving ribs with smaller inconspicuous ones between them, 

 crossed by faint plications (more evident on the smaller whorls), producing 

 nodosities which, on the four principal ribs, and especially on the third one, 

 counting from the suture toward the base, rise to acutely pointed projections 

 separated by an incurved scallop of about twice the width of the projections ; 

 toward the aperture the ribs and nodosities become more equal in size ; base 

 flattened, impervious, sculptured with some fifteen close set flattened revolving 

 ribs crossed by impressed radiating lines of growth ; aperture nearly rectangu- 

 lar ; pillar straight, stout, not projecting, without a callus ; margin thin, a little 

 crenulated by the sculpture. Alt. 5.25. Basal diam. 4.75. Diam. of aper- 

 ture, 2.0. Alt. of same, 1.75 mm. 



Sigsbee, off Havana, 80 fms. 



Seguenzia formosa Jeffreys. 

 Rep. on Valorous Cruise, Proc. Roy. Soc, 1876, p. 200. 

 Station 16, 292 fms. Station 20, 220 fms. 



