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dark at the apex, sometimes with a white space next below the apex, 

 followed by a white spiral bund : with, on the upper whorls, two, and 

 on the lower whorls, three nearly equal spiral ridges, and many trans- 

 verse slender ridges, the intersections being well developed nodules ; 

 anteriorly with two additional smaller less strongly nodulous spiral 

 ridges : apex very acute : spire with the outlines nearly rectilinear : 

 whorls about nine, planulate, with the place of the suture distinguished 

 by a somewhat larger groove ; last whorl terminating very abruptly : 

 aperture suborbicular, rather small : canal short, nearly straight. 

 Mean divergence about 20^^ ; length .1 1 inch ; breadth .08 inch. 



Cerithium mirabile. Shell ovate conic, turrited, sinistrorsal : 

 white, with a sutural band of blackish brown, which commences a 

 few whorls below the light brown apex with an intervening white 

 space : v/ith a narrow very prominent sutural ridge, on which is the 

 band of blackish brown, and a stouter strongly nodulous spiral ridge 

 along the middle of the whorls, anteriorly with one or two additional 

 slightly nodulous spiral ridges : apex very acute : spire with the out- 

 lines rectilinear in the upper half, quite fusiform in the lower half: 

 whorls about fifteen, nearly planulate, with an indistinct suture; last 

 whorl very much smaller than the penult whorl : aperture suborbicu- 

 lar, extremely small : with two small canals, which are deflected 

 nearly at right angles to the axis of the shell, and are open only at 

 the extremity. This extraordinary species of subgenus Triphora is 

 remarkable for the minute size of the aperture. 



Mean divergence to the penult whorl about 20^ ; length .2 inch ; 

 breadth .062 inch ; length of aperture only .025 inch ! 



Cerithium exiguum. Shell long ovate conic, sinistrorsal : wax 

 color : with, on the middle whorls, two, and on the lower whorls, 

 three spiral ridges, of which the middle one is more slender, and nu- 

 merous transverse ridges, the intersections being well developed 

 nodules; anteriorly with three additional smaller less strongly nodu- 

 lous spiral ridges : apex very acute : spire with the outlines most 

 curvilinear along the middle, nearly rectilinear above and below : 

 whorls ten, planulate, with the place of the suture distinguished by a 

 somewhat larger groovje ; last whorl much smaller than the penult 

 whorl, gradually tapering to the end : aperture rather small, sub- 

 rhombic : canal very short, nearly straight. 



