134 



WEST COAST SHELLS 



each whorl is ornamented with a raised belt or gir- 

 dle, from which fact it takes its name. The aper- 

 ture is large, being half as long as the whole shell. 

 Several other rare species of this genus are known 

 to exist either in the cold waters of the north or in 

 the deep water off the more southern coasts. 



Figure 105 represents a very graceful 

 shell named ^urris opliioderma^ Dall, the 

 Pencilled Drill-shell {Drillia penicil- 

 lata). The spire consists of eight slender 

 whorls, the aperture is long, and the sur- 

 face is smooth, brownish, and marked 

 with delicate cross-lines of color. Tryon 

 maintained that this species is only a 

 variety of Drillia inermis^ Hinds. It is 

 distinctively a southern species. T^urris 

 pcnicillata^ Cpr., is a Mexican species, 

 which was confused with 'T^. inermis^ a 

 species already mentioned. 



Drillia tor OS a, Cpr., the Knobbed Drill-shell, 

 shown in Figure 106, is* found somewhat farther to 

 the north. It is rather less graceful than its 

 southern relative, and it is smaller also. 

 The surface is almost black, but each whorl 

 is ornamented with a spiral row of lighter 

 colored knobs. 



The third species, Drillia moesta^ Cpr., 

 the Doleful Drill-shell, resembles the last 

 species, but the whorls have cross-ribs in- 

 stead of knobs. It is a southern shell and is found 

 under stones between tides. Its color is brown or 



Fig. 105 



Fig. 106 



