CHLOROSTOMA. 175 



to 6, the upper ones with a strong carina midway between the 

 sutures, the last carinated at the periphery and above, generally 

 showing a less prominent carina on the base near the periphery ; 

 aperture oblique, columella oblique, arcuate ; umbilicus broad and 

 deep, with a spiral rib within. 



Alt. 26, diam. 40 ; alt. 35, diam. 44 mill. 



W. coast of S. America, from Callao to Valparaiso. 



Trochus luctuosus D'ORB., Voy. dan* VAmer. Merid., p. 409, t. 

 76, f. 16-19. PHILIPPI, Conchy I. Cab., p. 153, t. 25, f. 4, 5. 

 FISCHER, Coq. Viv., p. 106, t. 31, f. 3. T. bicarinatiis POT. ET 

 MICH., Galerie, i, t. 30. f. 1-3 (not T. bicarinatiis Lam., a fossil 

 species). T. carinatus KOCH, in PHILIPPI, Abbild., Trochus, t. 2, f. 

 3 (not T. carinatus Borson, a fossil species). Chlorostoma tropido- 

 phorum A. AD., P. Z. S., 1851, p. 183. 



The wide umbilicus and strongly keeled whorls* separate this 

 form from the other species. 



C. TRIDENTATUM Potiez et Miclmud. PI. 28, figs. 47, 48. 



Shell minutely perforate, conoidal, elevated, heavy and solid, 

 black or purplish ; whorls 5 to 6, slightly convex, smooth, the last 

 with rounded periphery ; base somewhat flattened, deeply eroded in 

 front of the aperture; aperture small, oblique, the outer lip thick 

 and lirate within, the columella short, oblique, distinctly tridentate 

 at the base ; umbilicus circular, minute. 



Alt, 19-22, diam. 15-18 mill. 



Coasts of Peru and Chili. 



Monodonta trideutata P. ET M., Galeri? du Mus. de Douai, i, p. 

 321, t. 29, f. 16, 17. Trochus tridentatus PHIL., Conchy 1. Cab., p. 

 153, t. 25, f. 3. FISCHER, Coq. Viv., p. 172, t. 57, f. 2.T. tridens 

 MKE. in PHILIPPI. Abbild., Trochus, t. 4, f. 10. T. stenomplialus 

 JONAS, Zeitschr. f. Mai., , p. 114. T. microstomus D'ORBIGNY, 

 Voy. dans I'Amer. Merid., p. 410, t. 76, f. 20, 21. 



( Omphalius.) 

 C. VIRIDULUM Gmelin. PI. 29, figs. 54-56. 



Shell umbilicate, conoidal, solid, whitish-grayish or greenish, 

 radiately striped above with crimson or rich brown, beneath spotted 

 or radiately striped with the same color ; spire rather obtuse, short ; 

 whorls 6, convex, encircled by spiral lirse which are more or less 



