12 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Murex petri Dali, 1900 
See Part I, Plate 28, fig. 7 
Nautilus, 14:37. Proceedings of the United States National Museum, 24; PI. 34, fig. 7, 
1902. 
Shell solid, when perfect, with an acute produced apex of four or five 
whorls, followed by four ordinary whorls; nepionic shell with convex 
shouldered whorls with up to six rounded varices, spirally sculptured, with 
rather prominent threads; color of the shell, purplish-brown more or less 
minutely mottled or articulated with paler spots; surface with obsolete 
flattish spiral threads stronger on the backs of the varices, and, when 
perfect, also showing very minute spiral striation; whorls between the 
varices with a single not very prominent knob; varices flattish, with five 
or six projecting points or digitations separated by shallow emarginations 
and slightly excavated on the forward face; these projections are not re¬ 
curved ; anterior face of the varices covered with profuse, crinkled, imbri¬ 
cating lamellae; a marked sulcus between the anterior digitation and the 
canal; aperture ovate, thickened, with a projecting yellowish margin with¬ 
out any dentiform process; the interior shows about six nodular denticles 
on the anterior two-thirds of the outer lip; canal closed, rather long, 
sharply curved to the right. Long, of shell, 65; lat., 32; of aperture, 15.6; 
lat., 11.5 mm. (Dali.) 
Type in United States National Museum. Type locality, San Pedro, 
California, in deep water. 
Range. Santa Barbara to San Pedro, California. 
Subgenus Triremis Bayle, 1884 
Murex santarosanus Dali, 1905 
Plate 32, fig. 3 
Nautilus t 19:14. 
Shell small for the subgenus, with about six whorls, each bearing from 
five to seven, strong, low reflexed varices, with a prominent, short, reflexed 
and indexed grooved spine at the shoulder of the whorl; nuclear whorls 
one and a half, smooth, minute; nepionic whorls two and a half, with 
whorls tabulate, two strong spiral cords at the shoulder, the varices thin, 
irregular laminae low and obscure; subsequent whorls, with five (increas¬ 
ing in the adult to seven), strong, anteriorly crispate, amber-brown varices, 
under which the whorls are tabulate, the intervening spaces whitish, nearly 
smooth or with very obscure revolving lines or threads; base of the whorls 
[310] 
