394 CALLIOSTOMA. 



Maine Northward ; Scandinavia ; N. Scotland ; fossil in the English 

 Crag. (40-90 fms.) 



Trochus occidentalis Migh. & Ad., Bost. Journ. Nat. Hi.>^t. iv, p. 

 47, t. 4, f. 16 (1841).— Jeffreys, Brit. Conch, iii, p. 333 ; v, t. 63, 

 f. 7. — Gould, Invert, of Mass., ed. Binney, p. 286, fig. 548. — Margar- 

 ita alabastrum. Beck, in Loven, Ind. Moll. lit. Scandin., p. 20 (1846). 

 — T. alabastrum Beck, Philippi, Concliyl. Cab., p. 91, t. 15, f. 14. 

 —Forbes & Hanley, Hist. Brit. Moll, ii, p. 497, t. 66, f. 7, 8.— 

 Tr. formosus Forbes, Ann. Mag. Nat. Hist, xix, p. 96, t. 9, f. 1 

 (1847).— Searles Wood, Crag Moll., p. 125, t. 13, f. 2.— 2V. 

 quadricinctus S. Wood, olim. — Zizyphinns alabastrum Beck, Reeve 

 Conch. Icon., f. 46. — T. occidentalis Migh., Sars, Moll. Reg. Arct. 

 Norv., p. 142, t. 9, f. 7, t. iv, f. 5 (dentition). 



An exquisite little gem, like an opal in its iridescence, with smooth, 

 narrow, more opaque riblets. It has the same distribution as several 

 species of Margarita. 



( Groiip of C. exasj)eratum Pennant.^ 

 C. exasperatum Pennant. PI. 17, figs. 20, 42 ; pi. 18, figs. 5-8. 



Shell small, turreted, solid, thick ; color purplish-brown, blackish- 

 purple or red, with white longitudinal lines or stripes, the base 

 rad lately striped or dotted with white. Surface lusterless, the whorls 

 encircled at the peripheral carina by a rounded granulate ridge, 

 above this with 4 spiral granose lir?e, the interstices densely, 

 regularly marked by elevated lamellar stri?e ; base encircled by 6 

 concentric line, narrower than the densely radiately striate inter- 

 stices ; apical whorls red. Spire very high; whorls 9-10, the last 

 angular, aperture quadrangular, throat brilliantly iridescent, basal 

 margin thickened, columella subvertical, obliquely truncate below. 



Alt. 12, diam. Ql mill. ; alt. 10, diam. 6^ mill. 



Mediterranean, Adriatic and Black Seas ; Atlantic Ocean, England 

 and Belgium to Canaries; Madeira and Azores Is. 



T. exasperatus Pennant, Brit. Zool. iv, p. 126 (1777).— Jeffreys, 

 Brit. Conch, iii, p. 324 ; v, p. 203, t. 63, f 4.— Fischer, Cocj. Viv., 

 p. 266, t. 89, f 1.— B., D. & D., Moll, du Rouss., p. 362, t. 43, f. 1- 

 7. — And of other authors.- — T. conulus Dacosta, Brit. Conch., p. 40, 

 t. 2, f. 4. — T. viimdus, striatus, etc., Chemnitz, Conchyl. Cab., v, p. 

 30, t. 1529. — T. minutus Chem. Deshayes, in Lam., An. s. Vert, ix, 

 p. 151. — T. erythroleucos Gmel., Syst. Nat. xiii, p. 3581. — Lam., 

 An. s. Vert, vii, p. 30. — T. exiguus PuLT.,Cat. Dorset., p. 48, t. 12, 



