512 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
Figure 2.—Living limpet, A4cmaea, is shown attached to a rock, its shell raised somewhat 
higher above the fleshy foot than normal. Limpet’s front faces to the left. 
Ficure 3.—Bilateral symmetry of chiton (left) with mouth and anus at opposite ends, 
contrasts with curled, one-sided patellid and snail (right) where same organs lie in close 
proximity. 
