250 WEST COAST SHELLS 



appears plainest on dead shells; the live ones are 

 darker, smoother and less brilliant. Var. crucifera^ 

 Dall, is a southern form, found at San Pedro and 

 San Diego, which has four broad white rays starting 

 from the apex, the posterior one becoming rapidly 

 V-shaped. The ground color is brownish gray. 



Fissuridea as p er a^ 

 Esch., the Rough Key- 

 hole-limpet, is well 

 shown in Figure 249. 

 This shell is quite coni- 

 cal, with a small, oval 

 hole at the top, very 



Fig. 249 j.^ ,, \_ -^ 



diTierent irom the nar- 

 row, oblong slit of the last species. The edge is 

 wrinkled, the outside color is gray, with dark, pur- 

 plish ra3^s running down from the apex, while the 

 interior is white. The common size is rather less 

 than that of the cut, though some old specimens are 

 very much larger. 



Fissuridea murina^ Dall, the White Keyhole-lim- 

 pet, is the next one of this interesting series that we 

 are to consider. This species has a much smaller 

 and more delicate shell than that of the last one, 

 though in some respects they resemble each other. 

 The shell is oblong in shape, with curved ends. The 

 roundish oval hole is one-third of the shell's length 

 from one extremity, and there are numerous fine 

 ribs, checked by concentric ridges. The color is pure 

 white, at least in dead specimens, and the length is 

 about 1 5; mm., a little less than the diameter of a 

 silver dime. 



