CHLOKOSTOMA. 



185 



above, and these are articulated with white ; the periphery is obtusely 

 subangular, and bears two more conspicuous lira? articulated with 

 white, between which there are several lirula? ; the base is rather 

 flattened, concave in the middle around the umbilicus, and white, 

 with about 6 rather strong concentric line articulated with dark 

 spots; the outer part of the base is encircled by a zone of very 

 minute spiral ribs ; aperture oblique, rounded-quadrate ; columella 

 sinuous, arcuate; umbilicus white within, bordered by a strong 

 spiral rib which terminates in a tooth at the base of the columella, 

 beneath which is another smaller similar denticle. 

 Alt. 7, diam. 8 mill. 



C. IMPRE.SSUM Jonas. PL 63, figs. 8, 9. 



Shell narrowly and profoundly perforate, rather thick, conoid, 

 dull cinereous, ornamented with castaneous radiating flammules ; 

 whorls 6, rather convex, spirally finely lirate, the lira? 7 to 8 on the 

 penultimate whorl, 5 on the preceding; last whorl rounded, com- 

 pressed below the suture above, somewhat convex beneath, and 

 provided with about 10 concentric lira? ; aperture slightly dilated, 

 ovate, the lip plicatulate within ; columella thin in the middle, 

 arcuate, concave, bearing 2 or 3 tubercles below ; columellar callus 

 thick, green, slightly impinging upon the umbilicus. 



Alt. 13, diam. 13 mill. (Fischer.) 



W. coast S. America (.*); Mazatlan (f). 



Trochus impressus JONAS, in PHILIPPI, Conchyl. Cab., p. 318, t. 

 45, f. 6. FISCHER, Coq. Viv., p. 252, t, 85, f. 2. T. corvus PHIL., 

 Zeitschr.f. Mai., 1849, p. 152. (Error). 



C. SCALAR E Anton. PL 29, figs. 70-73. ' 



Shell broadly, deeply umbilicated, conical, white, nearly uni- 

 colored, (1) articulated on the ribs with reddish or olive-brown 

 dots, (2) tinged with pinkish or olive all over and dotted with a 

 darker self-color on the ribs, (3) with broa I radiating pinkish, 

 olivaceous or yellowish maculations above, maculated or speckled 

 on the base. Spire generally elevated, sometimes scalariform, 

 pointed, conical, the apex acute ; sutures deeply marked ; whorls 6 

 to 8, quite convex, obliquely striate, spirally lirate, the lirre generally 

 rather low, but sometimas elevated, cord-like, and numbering from 

 7 to 12 on the penultimate whorl. The lirse are rather irregularly, 

 slightly crenulated ; they are unequal in size, one or two about the 

 middle of the upper surface generally being larger, causing a slight 



