PIERCED SHELES AND CHITONS 261 
dingy. This mollusk is seldom found near the 
shore, as it lives wholly below the tides, and must 
be gathered by dredging. 
Lucapinélla callomarginata, Cpr., the Southern 
Keyhole-limpet, (Fissurellidea calliomarginata), 
is a small species, living below tide-mark, and 
occasionally found from San Pedro southward. 
The shell is low arched, with a rather large, oblong 
hole and roughened rays. The margin is crenu- 
lated, the interior white, and the exterior gray, or 
marked with dark rays; length, 19mm. 
Megatebénnus bimaculatus, Dall, the 
Spotted Keyhole-limpet, Figure 294, 
(Fissurellidexa bimaculata). These long 
names apply to a little shell which ocea- 
sionally grows to a length of 16mm., though many 
specimens are much smaller. The hole is very 
large for the size of the shell, and on either end 
of it are dark rays, making the two spots, from 
which it is named. Sometimes the whole shell is 
colored, with darker rays on the sides. The 
interior is white, though the spots sometimes show 
through. It is reported from British Columbia as 
living on the roots of the great seaweed, Macro- 
eystis. The animal is much larger than the shell, 
part of which is concealed by the mantle. 
There are very odd creatures under the stones 
which lie along the rim of the ocean. If you go 
down at low tide and turn the rocks over, one by 
one, you will be surprised at the number of singu- 
lar beings which stare up at you in blank amaze- 
ment, and then rush away into obscure places, as 
fast as their ten or fourteen legs will carry them. 
Fig. 294 
