362 CALLIOSTOMA. 



interstices are chocolate colored. Figure 49 of pi. 67 represents one 

 of these. From C. costatum this species may be known by its flatter 

 whorls, more angular periphery, lighter color, etc. 



C. COSTATUM Martyn. PL 16, figs. 6, 9 ; pi, 18, fig. 16. 



Shell conical, rounded at periphery, base flattened ; imperforate ; 

 solid ; dark chestnut colored, the spiral riblets lighter, apex dark, 

 usually purple. Surface encircled by numerous spiral smooth 

 riblets, their interstices closely finely obliquely striate ; riblets usually 

 7 to 9 on the penultimate whorl, about 9 on the base. Spire conic ; 

 apex acute ; sutures impressed. Whorls about 7, convex, the last 

 rounded (or a trifle angled) around the lower part, slightly convex 

 beneath ; aperture rounded, oblique, outer lip fluted w'thin, with a 

 beveled opaque white submargin ; throat pearly, iridescent; colu- 

 mella simple, arcuate. Alt. 20, diam. 18 mill. 



Sitka to Monterey and Sta. Barbara Id. 



Trochus eostatiis jNIart., Univ. Conch., t. 34 (1784). — Philippi 

 Conehyl. Cab., p. 275, t. 40, f 8 (not Trochus costatus Gmel. 1788, a 

 form of Lamprostoma). — Tr. filosns Wood, Index test, suppl., t. 5, f. 

 23 (no description).— Fischer, Coq. Viv., p. 199, t. 64, f S.—Zizy- 

 phiims filosus Wood, Reeve, Conch. Icon., f 27. — Tr. ligatus Gould, 

 U. S. Expl. Exped., 1. 12, £ 201. — Tr. castaneus (Nuttall ms) Forbes, 

 P. Z. S. 1850, p. 271, t. 11, f. 9. — Calliostoma costatam of American 

 authors. — C. splendens Carp., Proc. Cal. Acad, iii, p. 156 {teste 

 Dall, Am. Jour. Conch, vii, p. 126). 



A species very abundant along the northern Pacific coast; of its 

 mutations Dr. Dall says : This species passes through a number of 

 variations, which, however, do not obscure the specific characters. 

 The ribs are usually yellowish, smooth with reddish-brown inter- 

 spaces. The apex is blue when eroded. The whole sometimes has 

 a more or less olivaceous cast. The yellow of the apical ribs is 

 usually interrupted by patches of brown. This is sometimes con- 

 tinued on the lower whorls, when tlie three ribs nearest the suture 

 and often one or two on the carina of the whorls are prettily painted 

 with alternate patches of dark brown and greenish-wliite. The ribs 

 are more or less prominent, some specimens having them quite sharp 

 while in others they are hardly raised. In one other exquisite 

 variety the three sutural ribs and their interspaces are of a very rich 

 purple-blue, which is not due to erosion. The umbilical rib is some- 

 times salmon-colored. The nacre is of great brilliancy. Found from 



