SHEEES Without CANALS 231 
clings. Two .views are given 
of its shell, both of which rep- 
S resent unusually large speci- 
BYe2e mens. Figure 252 gives a good 
view of the shell as it appears from above, while 
the other figure shows a side elevation of the same. 
Internally the shell is chalky white with various 
dark markings, which sometimes bring out ‘‘the 
owl’’ very distinctly. Look for a picture of that 
bird in various shells of this class. 
Limpets are easily collected if they are suddenly 
lifted by means of a broad-bladed knife, but if they 
have been previously startled it is best to let them 
alone, since you will be likely to break the shell if 
you persist in your endeavor. In some countries 
they are eaten, and vast numbers are used by the 
fishermen as bait. Notice carefully the broad foot, 
the mantle and gills, and the short head with its 
mouth and tentacles. If a specimen is dissected, 
the lingual ribbon may easily be obtained from the 
mouth, and with a low-power microscope the beau- 
tiful rows of teeth may easily be made out. After 
the animal has been removed from the shell, 
observe the horseshoe-shaped muscle-sear. 
Acmea patina, Ksch., the = 
Plate Limpet, Figure 254, 
is one of the most common 
kinds. The shell is oval, 
flattened, with an indistinct apex near the center. 
From this radiate fine striew, which are often indis- 
tinct. The shell is also often partly overlaid with 
brownish sea-growths. Young specimens are 
Fig. 254 
